DE102011009937A1 - Method for measuring charge transfer property of semiconductor layer on thin-film solar cell, involves comparing detected measurement value with comparison measurement value that is detected using outer energetic influence of layer - Google Patents

Abstract

The method involves contacting a substrate (3) with a portion (2.1) of a stripline (2), and coupling a semiconductor layer (4) to another portion (2.2) of the stripline. Electromagnetic waves with microwave frequency are capacitively-coupled into the former portion of the stripline using a layer of dielectric fluid and decoupled from the latter portion of the stripline. A measurement value at the stripline is detected during coupling of the waves. The detected value is compared with a comparison measurement value that is detected using an outer energetic influence of the semiconductor layer. An independent claim is also included for an arrangement for measuring electrical characteristics of a semiconductor layer on an electrical conductive substrate.

Description

The invention relates to a method and an arrangement for characterizing semiconductor layers on a conductive substrate.

The efficiency of such a complex component as a modern thin-film solar cell essentially depends on the properties of the layers, in particular of the semiconductor layers involved, from which the thin-film solar cell is constructed. Usually, a number of semiconductor layers are present over a substrate. The number of semiconductor layers is on the side facing away from the substrate by a transparent protective layer, such. B. a glass layer completed.

It is difficult to unequivocally attribute a possible malfunction of the thin-film solar cell to the respective properties of a specific semiconductor layer, since the individual semiconductor layers in a finished thin-film solar cell can not be directly examined. Particularly difficult are studies on semiconductor layers on conductive substrates, such. B. on such as the metallic back contact of a solar cell. Of interest are the composition, structure, and band gap, but especially the properties of the charge carriers in the layers, such as the net carrier concentrations of majority and the lifetime of minority carriers.

So far, one could apply the comprehensive analysis especially on volume semiconductor crystals. In particular, in recent years, various versions of the QSSPC method (quasi steady-state photo conductance) for the determination of the lifetime in Si have prevailed ( Sinton et al. (1996) Appl. Phys. Lett., 69: 2510-2512 ). In the case of thin semiconductor layers, on the other hand, the characterization of electrical properties was mostly carried out on the basis of the detection of the charge transport in the semiconductor layers in the lateral direction, the semiconductor layers having been previously deposited on a nonconductive substrate for the purpose of testing. A method is known van der Pauw (1958, Philips Research Reports 13, No. 1, 5. 1-9) for determining the parameters of majority carriers.

This method has two major disadvantages. First, due to the anisotropic polycrystalline structure of thin semiconductor layers and the grain boundary, charge transport in the lateral direction is substantially different from charge transport in the direction perpendicular to the layer surface. According to the van der Pauw method, the lateral transport is investigated, whereas for the function of the solar cell the vertical charge transport, in particular in the absorber layer, is of great importance.

Second, the growth of the semiconductor layer on a foreign, insulating substrate usually proceeds differently than on the electrically conductive back contact of a solar cell. Due to these two significant disturbances, the measurement data of test structures on foreign substrates for the properties of the same layers in the solar cell are only limited to meaningless.

Other measuring methods are known. Electrical measurements of the surface tension change and methods using a Kelvin probe are difficult to evaluate quantitatively since the initial band bending is not known. In optical ellipsometric measurements, the relationship between optical absorption and DC charge transport is not clear. In addition, ellipsometric measurements require smooth surfaces and interfaces. Time-resolved (transient) photoluminescence (TRPL) is used, but the typical lifetime, especially in thin film solar cells, is already on the order of the pulse duration of a typical pulsed laser. Attempts to measure the perpendicular conductivity directly by applying a conductive contact on the semiconductor layer, fail because of shunts and because of unknown and poor quality contact with the low-doped semiconductor, z. B. an absorber layer.

The invention has for its object to find a new way to determine changes in the charge transport properties of a semiconductor layer, the investigations in the direction perpendicular to the layer surface and a reproducible contacting the semiconductor layer allows.

• – Kontaktieren des Substrats mit einem ersten Abschnitt einer planaren Mikrowellenleitung;
• – Herstellen einer Ankopplung der Halbleiterschicht an einen zweiten Abschnitt der planaren Mikrowellenleitung, wobei die Ankopplung über die nach oben weisende Oberfläche der Halbleiterschicht kapazitiv erfolgt;
• – Einkoppeln von elektromagnetischen Wellen einer Mikrowellenfrequenz in den ersten Abschnitt der planaren Mikrowellenleitung und Auskoppeln aus dem zweiten Abschnitt der Mikrowellenleitung;
• – Erfassen mindestens eines Messwertes an der planaren Mikrowellenleitung während die Mikrowellen einer Mikrowellenfrequenz eingekoppelt sind;
• – Vergleichen des bei einer Mikrowellenfrequenz erfassten Messwertes mit mindestens einem nachfolgenden Vergleichsmesswert, der bei einer äußeren energetischen Beeinflussung der Halbleiterschicht erfasst wird.

The object is achieved in a method for measuring electrical properties of at least one semiconductor layer, which is located on an electrically conductive substrate and is thus electrically short-circuited in the lateral direction by the substrate, with the following steps:

• - contacting the substrate with a first portion of a planar microwave line;
• - Producing a coupling of the semiconductor layer to a second portion of the planar microwave line, wherein the coupling via the upwardly facing surface of the semiconductor layer is capacitive;
• - coupling electromagnetic waves of a microwave frequency into the first section of the planar microwave line and coupling out of the second section of the microwave line;
• - detecting at least one measured value on the planar microwave line while the microwaves are coupled to a microwave frequency;
• - Comparing the measured value detected at a microwave frequency with at least one subsequent comparison measured value, which is detected at an external energetic influence of the semiconductor layer.

The basic idea of the invention is based on the evaluation of the change of the stationary microwave conductivity of the semiconductor layer as a function of the external energetic influence, without transients being recorded and the microwave resonance being determined in the determination of the carrier concentration.

The capacitive coupling of the semiconductor layer to the second section of the microwave line is effected by a layer (liquid layer) of a dielectric liquid applied to the surface of the semiconductor layer, the layer thickness of the liquid layer being kept constant.

An energetic influencing of the semiconductor layer can take place by irradiation with an electromagnetic radiation. An energetic influence can consist both in an increase (eg: heating, excitation) and in a reduction (eg cooling, shading) of the semiconductor layer.

In a preferred embodiment of the invention, the energetic influencing of the semiconductor layer is effected by a change in the temperature of the semiconductor layer.

This can take place by means of irradiation through a contacting element of the liquid layer connected to the second section of the microwave line. The contacting element and the liquid layer are then substantially transparent to the radiation used.

• – Erfassen mindestens eines Referenzmesswertes an dem zweiten Abschnitt der Mikrowellenleitung, während die elektromagnetischen Wellen der Mikrowellenfrequenz eingekoppelt sind und keine Halbleiterschicht vorhanden ist;
• – Erfassen mindestens eines Messwertes an dem zweiten Abschnitt der Mikrowellenleitung, während die elektromagnetischen Wellen der Mikrowellenfrequenz eingekoppelt sind und eine Halbleiterschicht vorhanden ist.

In a further embodiment of the method according to the invention, the following additional steps can take place:

• Detecting at least one reference measured value at the second section of the microwave line, while the electromagnetic waves are coupled to the microwave frequency and no semiconductor layer is present;
• - Detecting at least one measured value at the second portion of the microwave line, while the electromagnetic waves of the microwave frequency are coupled and a semiconductor layer is present.

It is possible that temporally successive electromagnetic waves, each with a microwave frequency from a selected range of microwave frequencies are coupled into the microwave line until a cutoff frequency is found by a predetermined selection criterion is met.

Such a predetermined selection criterion may consist in the determination of the cut-off frequency ω _{G of} the microwave transmission function satisfying the condition 1 / ω _G C _H = R _H , where R _{H is} the electrical resistance of the semiconductor layer and C _{H is} the known capacitance of the semiconductor layer.

In an advantageous embodiment of the method, the sample carrier, including the liquid layer, is taken into account by evaluating the reference measured values.

An advantage of the method is that if at least one property of the semiconductor layer is influenced by a change in an energy applied to the semiconductor layer, the influence leads to a detectable change in the cutoff frequency.

The change of the cutoff frequency can be effected by means of a working according to the lock-in principle device.

• – einer planaren Mikrowellenleitung, die in einen ersten Abschnitt und einen zweiten Abschnitt unterteilt ist, wobei der erste Abschnitt und der zweite Abschnitt voneinander separiert sind;
• – Mitteln zur elektrisch leitfähigen Kontaktierung des Substrats durch den ersten Abschnitt;
• – Mitteln zur gesteuerten Erzeugung von elektromagnetischen Wellen mit mindestens einer Mikrowellenfrequenz und zur Einkopplung der elektromagnetischen Wellen in den ersten Abschnitt an einem Eingang der Mikrowellenleitung;
• – einem Kontaktierungselement zur Herstellung eines elektrisch leitenden Kontakts zwischen dem zweiten Abschnitt und dem ersten Abschnitt der Mikrowellenleitung, wobei das Kontaktierungselement mit der vom Substrat abgewandten Oberfläche der Halbleiterschicht kapazitiv kontaktierbar ist;
• – Mitteln zur Erfassung mindestens eines Messwertes an dem zweiten Abschnitt an einem Ausgang der Mikrowellenleitung;
• – Mittel zum Vergleichen des bei einer Mikrowellenfrequenz erfassten Messwertes mit mindestens einem nachfolgenden Vergleichsmesswert, der bei einer äußeren energetischen Beeinflussung der Halbleiterschicht erfassbar ist.

The object is further achieved by an arrangement for measuring electrical properties of at least one semiconductor layer which is located on an electrically conductive substrate. The arrangement is to be described with:

• A planar microwave line divided into a first portion and a second portion, the first portion and the second portion being separated from each other;
• - Means for electrically conductive contacting of the substrate by the first section;
• - means for controlled generation of electromagnetic waves having at least one microwave frequency and for coupling the electromagnetic waves in the first section at an input of the microwave line;
• A contacting element for producing an electrically conductive contact between the second section and the first section of the microwave line, wherein the contacting element is capacitively contactable with the surface of the semiconductor layer facing away from the substrate;
• - means for detecting at least one measured value at the second section at an output of the microwave line;
• - Means for comparing the measured value detected at a microwave frequency with at least one subsequent comparison measured value, which is detectable in an external energetic influencing of the semiconductor layer.

The planar microwave line may be given by flat elements which are conductive to microwaves and spaced from one another. For example, a planar microwave line may be a stripline, as known in the art. In this case, a strip line runs parallel to a plate electrode and is separated from it by a non-conductive medium, for. As air or a material of a semiconductor board, spaced.

For capacitive contacting of the semiconductor layer, a liquid layer of a dielectric liquid is provided.

It is of great advantage if a spacer for maintaining the thickness of the liquid layer between the semiconductor layer and the contacting element is present.

It is furthermore advantageous if releasable means for generating pressure and fixing the contacting element with respect to the second section of the microwave line and with respect to the semiconductor layer are attached to the contacting element.

• – Mittel zum Erfassen mindestens eines Referenzmesswertes an dem zweiten Abschnitt der Mikrowellenleitung, während die elektromagnetischen Wellen der Mikrowellenfrequenz eingekoppelt sind und eine metallische Referenzprobe ohne Halbleiterschicht und
• – Mittel zum Vergleichen des bei der Mikrowellenfrequenz erfassten Messwertes mit mindestens dem bei der Mikrowellenfrequenz erfassten Referenzmesswert vorhanden sein.

In a further embodiment of the arrangement according to the invention

• - Means for detecting at least one reference measured value at the second portion of the microwave line, while the electromagnetic waves of the microwave frequency are coupled and a metallic reference sample without semiconductor layer and
• - Means for comparing the detected at the microwave frequency measurement with at least the detected at the microwave frequency reference measurement be present.

It is a preferred embodiment of the arrangement if the means for comparing the at least one detected measured value and the at least one detected comparative measured value or reference measured value contain at least one element operating according to the lock-in principle.

In an arrangement according to the invention, a capacitive coupling of the semiconductor by the liquid with a high dielectric constant, for. As water or glycerol, realized, so that the contact problem is completely solved. This way of contacting the surface of the semiconductor layer is hardly sensitive to local short circuits because of the missing semiconductor layer (shunts). It also does not destroy the semiconductor layer and is, with the aid of a spacer to ensure a constant thickness of the liquid layer of the liquid, well reproducible. In contrast to the classical QSSPC, it is not the DC impedance that is measured but a microwave impedance between an input and an output of the microwave line. The measurement can be done with a network analyzer or, more simply, with a microwave generator at the input and a microwave detector, e.g. B. a diode sensor, be realized at the output.

It is also possible in further embodiments of the invention that the plate electrode is strip-shaped.

The microwave signal is evaluated by means of lock-in technology in synchronization with the energetic influencing (eg by means of irradiation) of the semiconductor layer. The irradiation of the semiconductor layer is done by a transparent contacting element, for. B. of ITO-coated glass.

The principle of operation of the method can be explained so that by changing the concentration of charge carriers, for. B. depending on the irradiation intensity, directly the resistance of the semiconductor R _{H is} affected.

In a preferred embodiment of the invention, the capacitance C _{H is formed} by the semiconductor layer itself and is known from the given dielectric constant of the semiconductor and the dimensions of the semiconductor layer. The capacity C _{L of} the liquid layer is predetermined by the liquid used and should be as large as possible.

At a microwave frequency much higher than the cutoff frequency, the reactance X (C _H ) = 1 / iω C _{H is} very small compared to R _H. Thus, R _{H is} practically shorted and its change due to irradiation or other energetic influence does not affect the impedance of the semiconductor layer. At this high microwave frequency, the sample holder behaves like a capacitor with a pure reactance. At a low microwave frequency much lower than the cut-off frequency is 1 / ω C _H »R _H so that the capacitance C _{H of} the semiconductor layer is negligible. A change in R _H results in a large change in impedance. It can be shown that the boundary condition 1 / ω C _H = R _H at a cutoff frequency (ω _G = 1 / (εε ₀ ρ) • (1) is fulfilled.

Here, the limit frequency ω _{G is} the angular frequency of the microwave radiation corresponding to the limiting case, εε ₀ the absolute dielectric constant and ρ the resistivity of the semiconductor. Since the dielectric constant for various semiconductors is known and changes little, the measurement of the cut-off frequency ω _G allows an immediate determination of the specific resistance ρ of the semiconductor in the semiconductor layer.

A frequency of 1 GHz and ε = 10 corresponds to the specific resistance ρ = 180 Ohm · cm. This value corresponds approximately to an unlit low-doped solar cell absorber. In this respect, the resistance of the unlit semiconductor layer can be determined. When increasing the intensity of an irradiation (exposure), the specific resistance ρ decreases and the limit frequency ω _{G increases} . To determine the lifetime of minority carriers according to the QSSPC principle, the microwave frequency is kept constant and the irradiation intensity is varied.

The invention will be explained in more detail with reference to figures and embodiments. The pictures show:

1 a first embodiment of the inventive arrangement in a) a side view and b) in plan view;

2 A second embodiment of the inventive arrangement as a block diagram and

3 the first embodiment of the inventive arrangement as an equivalent circuit.

As essential elements of an inventive arrangement are in 1a) a sample holder 1 with a contact foot 8th for contacting a second section 2.2 one as a stripline 2 formed planar microwave line, a horizontally arranged planar carrier 7 as a contacting element, on its underside with a coating 7.1 is provided, one at an input of the stripline 2 arranged microwave generator 10 and one at an output of the stripline 2 arranged microwave detector 11 shown.

The stripline 2 is over an electrically conductive plate electrode 2.3 and spaced therefrom and has a uniform width. Between the stripline 2 and the plate electrode 2.3 there is an electrically non-conductive plastic. From the input (generator side) of the stripline 2 out extends a first section 2.1 the stripline 2 parallel to the plate electrode 2.3 towards the output A (detector side) of the stripline 2 , The first paragraph 2.1 is from the second section 2.2 separated by a gap.

On the second section 2.2 is the contact foot 8th at the end of the second section 2.2 put on the first section 2.1 is closest. On the contact foot 8th is the carrier made of glass 7 placed horizontally, wherein the coating formed from a layer of indium tin oxide 7.1 on the contact foot 8th rests and the contact foot 8th through the coating 7.1 electrically conductive contacted.

The carrier 7 protrudes, starting from the contact foot 8th , over a partial length of the first section 2.1 , Between the first section 2.1 and the towering part of the vehicle 7 is an electrically conductive substrate 3 with a semiconductor layer applied thereon 4 arranged so that through the substrate 3 the first paragraph 2.1 is contacted and the semiconductor layer 4 points upwards. As a substrate 3 is copper, as a semiconductor layer 4 a layer CuInS _{2 is selected} with a layer thickness of 1.5 microns. A base of the substrate 3 with the semiconductor layer 4 is as wide as the width of the stripline 2 ,

One between the semiconductor layer 3 and the coating 7.1 remaining gap is with a liquid layer 6 filled with glycerine. The liquid layer 6 is from an annular spacer 5 whose task is to retain the glycerin and to ensure a predetermined distance between the semiconductor layer 4 and the coating 7.1 consists. The semiconductor layer 4 has a known electrical capacitance C _H and an electrical resistance R _H. The liquid layer 6 represents a capacity C _L.

The spacer 5 can be designed differently in other versions. It can for example consist of at least three balls, ring segments, z. B. Viton, or even from drops of an adhesive.

The first paragraph 2.1 and the second section 2.2 are through the sample holder 1 , the liquid layer 6 , the semiconductor layer 4 and the substrate 3 capacitively coupled.

By one on the carrier 7 acting force F is the carrier 7 on the contact foot 8th and the spacer 5 pressed, causing both the wearer 7 as well as the spacer 5 as well as the substrate 3 are held.

The force F can be achieved by releasable means for generating and fixing the pressure Contacting element (not shown) such as spring systems or clamping devices applied.

In further embodiments of the arrangement according to the invention, a holder of the elements of the sample holder 1 also different, z. B. positively, causes.

The carrier 7 sticks out as in 1 b) shown laterally over the stripline 2 , The larger width of the carrier 7 gives the same characteristic impedance across the plate electrode 2.3 like the sections of the stripline 2.1 and 2.2 as the carrier 7 at a greater distance to the plate electrode 2.3 located. In this respect, a reflection-poor contacting of the sample (substrate 3 with semiconductor layer 4 ) reached.

Through the microwave generator 10 are microwaves in the stripline 2 and into the plate electrode 2.3 be coupled. Through the microwave detector 11 microwaves are detectable and forwarded to other components of an arrangement.

Above the carrier 7 There are means (not shown) through which a certain energy is controlled by the wearer 7 , the coating 7.1 and the liquid layer 6 on the semiconductor layer 4 can be introduced. The elements carrier 7 , Coating 7.1 and liquid layer 6 are transparent to the energy while passing through the semiconductor layer 4 at least part of the energy is absorbed.

Based on an arrangement according to 1 is in 2 a second embodiment shown as a block diagram, based on which the inventive method is to be explained by way of example.

In the sample holder 1 is how to 1 described a substrate 3 with a semiconductor layer 4 held. By means of the microwave generator 10 Microwaves of a selected microwave frequency ω in the first section 2.1 of the stripline 2 and into the plate electrode 2.3 coupled.

Through the microwave detector 11 be on the detector side after the sample holder 1 Microwave detected and at one with the microwave detector 11 signal-conducting connected lock-in amplifier 13 forwarded. The through the lock-in amplifier 13 filtered and amplified signals appear on a display 14 shown. By a clock generator 12 that with a radiation source 9 and the lock-in amplifier 13 signal-conducting connected, become the lock-in amplifier 13 and the radiation source 9 clocked. By pulsed irradiation of the semiconductor layer 4 and the appropriately timed filtering and amplification of the signals, an increase in the sensitivity of the device is achieved.

The radiation source 9 is designed (eg, as an LED) that through them energy in the form of electromagnetic radiation on the semiconductor layer 4 is applied. carrier 7 , Coating 7.1 as well as liquid layer 6 are chosen so that they are largely transparent to the energy.

By choosing the microwave frequency ω of the coupled microwaves can by the microwave detector 11 frequency-specific electrical properties of the semiconductor layer 4 be recorded. The measured values recorded at the respective selected microwave frequencies ω can be stored and arbitrarily compared with one another, wherein measured values detected at a specific microwave frequency ω can be selected as comparison measured values.

It is possible, by choosing different microwave frequencies ω, to determine a limit frequency ω _G = 1 / (εε ₀ ρ) for which the boundary condition 1 / ω C _H = R _H holds.

At this cut-off frequency, the lock-in signal is attenuated by 3 dB compared to measurement at much lower frequencies. If the cut-off frequency ω _{G is} not technically achievable for a given sample and measurement setup, the cut-off frequency can be calculated by extrapolation of the microwave transmission measurement data obtained at lower frequencies using a theoretical model.

For more accurate determination of the effect of the sample holder 1 for the readings and for use in the theoretical model, a number of reference readings can be taken with a metallic reference sample equal in height to the thickness of the substrate 3 and semiconductor layer 4 is, but in which the semiconductor layer 4 is not applied. In the in 3 pictured equivalent circuit is then missing semiconductor layer 4 , so that the reactance of the Flussigkeitsschicht 6 can be determined directly from microwave transmission. From these measurements, the capacitance C _{L is} detected with a systematically changed microwave frequency ω and stored in association with the respective microwave frequencies ω.

Subsequently, this becomes the semiconductor layer 4 carrying substrate 3 into the sample holder 1 inserted and the same sequence of microwave frequencies ω go through to capture the respective measured values and store.

When microwaves are coupled in with the cut-off frequency ω _G , comparison measured values then become at different energetic influencing of the semiconductor layer 4 detected.

The measuring method was implemented with the following parameters: measurement frequency 12 GHz, layer 1.5 microns CuInS ₂ on copper as the substrate, periodically modulated light source was an LED having a large spectral bandwidth (white) or red (about 640 nm), both in the absorption range of the semiconductor of the semiconductor layer 4 , As the dielectric liquid, deionized water was used. The clock frequency of the clock generator 12 (lock-in frequency) was 65-80 Hz. It was observed a large lock-in signal at the low frequency of 1 GHz and a significant decrease in the lock-in signal level with an increase in the microwave frequency ω. The lock-in signal disappeared immediately upon the interruption of the light beam.

In the 3 the arrangement according to the invention is shown as a highly schematic equivalent circuit diagram. The semiconductor layer 4 is represented by its electrical variables resistance R _H and capacitance C _H , which are arranged in the sense of a resonant circuit. The liquid layer 6 is given by its capacity C _L.

From the microwave generator 10 in the first section 2.1 of the stripline 2 Coupled microwaves are frequency-dependent attenuated by the RC element formed by R _H and C _H. The RC element is capacitive via C _L to the sample carrier 1 and the second section 2.2 coupled. Through the microwave detector 11 are the microwaves at the second section 2.2 detectable.

The invention can be used in the fields of measurement technology, the characterization of semiconductor layers, in particular in the development and production as well as the quality control and assurance of thin-film solar cells and semiconductor technology.

LIST OF REFERENCE NUMBERS

1

sample holder

2

stripline

2.1

first section

2.2

second part

2.3

plate electrode

3

substratum

4

Semiconductor layer

5

spacer

6

liquid layer

7

carrier

7.1

coating

8th

contact foot

9

radiation source

10

microwave generator

11

microwave detector

12

clock generator

13

Lock-in amplifier

14

display

C _L

Capacity (the liquid layer 6 )

C _H

Capacitance (of the semiconductor layer 4 )

R _H

electrical resistance (of the semiconductor layer 4 )

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• Sinton et al. (1996) Appl. Phys. Lett., 69: 2510-2512 [0004]
• van der Pauw (1958, Philips Research Reports, 13, No. 1, 5. 1-9) [0004]

Claims (18)

Method for measuring electrical properties of at least one semiconductor layer, which is located on an electrically conductive substrate and is thus electrically short-circuited in the lateral direction by the substrate, with the steps: contacting the substrate ( 3 ) with a first section ( 2.1 ) a planar microwave line; Producing a coupling of the semiconductor layer ( 4 ) to a second section ( 2.2 ) of the planar microwave line, wherein the coupling over the upwardly facing surface of the semiconductor layer ( 4 ) takes place capacitively; Coupling electromagnetic waves of a microwave frequency (ω) in the first section ( 2.1 ) of the planar microwave line and decoupling from the second section ( 2.2 ) of the microwave line; Detecting at least one measured value on the planar microwave line while the microwaves are coupled to a microwave frequency (ω); Comparing the measured value acquired at a microwave frequency (ω) with at least one subsequent comparison measured value, which is the result of an external energetic influencing of the semiconductor layer ( 4 ) is detected. Method according to Claim 1, characterized in that the capacitive coupling of the semiconductor layer ( 4 ) to the second section ( 2.2 ) of the microwave line through one on the surface of the semiconductor layer ( 4 ) applied layer [liquid layer ( 6 )] of a dielectric liquid, wherein the layer thickness of the liquid layer ( 6 ) is kept constant. Method according to claim 1, characterized in that the energetic influencing of the semiconductor layer ( 4 ) by irradiation with electromagnetic radiation. Method according to claim 1, characterized in that the energetic influencing of the semiconductor layer ( 4 ) by a change in the temperature of the semiconductor layer ( 4 ) he follows. A method according to claim 1, characterized in that the energetic influence by means of irradiation by a with the second section ( 2.2 ) of the microwave line connected contacting element of the liquid layer ( 6 ) through. A method according to claim 1, characterized in that the following additional steps are carried out: - detecting at least one reference measured value at the second section ( 2.2 ) of the microwave line, while the electromagnetic waves of the microwave frequency (ω) are coupled and no semiconductor layer ( 4 ) is available; Detecting at least one measured value at the second section ( 2.2 ) of the microwave line, while the electromagnetic waves of the microwave frequency (ω) are coupled and a semiconductor layer ( 4 ) is available. A method according to claim 6, characterized in that temporally successive electromagnetic waves, each having a microwave frequency (ω) from a selected range of microwave frequencies (ω) are coupled into the microwave line until a cutoff frequency (ω _G ) is found, by a predetermined selection criterion is satisfied. Method according to Claim 7, characterized in that the predetermined selection criterion consists in the determination of the cut-off frequency ω _{G of} the microwave transmission function satisfying the condition 1 / ω _G C _H = R _H , where R _{H is} the electrical resistance of the semiconductor layer ( 4 ) And C _{H is} the known capacitance of the semiconductor layer ( 4 ) are. A method according to claim 8, characterized in that a consideration of the sample carrier ( 1 ) including the liquid layer ( 6 ) by evaluation of the reference measured values. Method according to claim 7 or 8, characterized in that at least one property of the semiconductor layer ( 4 ) by a change on the semiconductor layer ( 4 ), which results in a detectable change in the limit microwave frequency (ω _G ). A method according to claim 10, characterized in that the change of the cut-off frequency (ω _G ) by means of a lock-in-principle working component takes place. Arrangement for measuring electrical properties of at least one semiconductor layer, which is located on an electrically conductive substrate, comprising: a planar microwave line, which is arranged in a first section (FIG. 2.1 ) and a second section ( 2.2 ), the first section ( 2.1 ) and the second section ( 2.2 ) are separated from each other; - means for electrically conductive contacting of the substrate ( 3 ) through the first section ( 2.1 ); - means for the controlled generation of electromagnetic waves having at least one microwave frequency (ω) and for coupling the electromagnetic waves in the first section ( 2.1 ) at an input of the microwave line; A contacting element for producing an electrically conductive contact between the second section ( 2.2 ) and the first section ( 2.1 ) of the microwave line, wherein the contacting element with the substrate ( 3 ) facing away Surface of the semiconductor layer ( 4 ) is capacitively contactable; Means for detecting at least one measured value at the second section ( 2.2 ) at an output of the microwave line; Means for comparing the measured value acquired at a microwave frequency (ω) with at least one subsequent comparative measured value which, in the case of an external energetic influencing of the semiconductor layer ( 4 ) is detectable. Arrangement according to claim 12, characterized in that as a planar microwave line a stripline ( 2 ) is available. Arrangement according to claim 12, characterized in that for the capacitive contacting of the semiconductor layer ( 4 ) a liquid layer ( 6 ) is provided a dielectric liquid. Arrangement according to claim 14, characterized in that a spacer ( 5 ) for keeping constant the thickness of the liquid layer ( 6 ) between the semiconductor layer ( 4 ) and the contacting element is present. Arrangement according to claim 12, characterized in that on the contacting element releasable means for pressure generation and fixation of the contacting element relative to the second section ( 2.2 ) of the microwave line and with respect to the semiconductor layer ( 4 ) are mounted. Arrangement according to claim 12, characterized in that it further comprises: - means for detecting at least one reference measured value at the second section ( 2.2 ) of the microwave line, while the electromagnetic waves of the microwave frequency (ω) are coupled and a metallic reference sample without semiconductor layer ( 4 ) is available; and - means for comparing the measured value acquired at the microwave frequency (ω) with at least the reference measured value detected at the microwave frequency (ω). Arrangement according to one of the preceding claims 12 to 17, characterized in that the means for comparing the at least one detected measured value and the at least one detected comparative measured value or reference measured value contain at least one element operating according to the lock-in principle.

Images