Electrical characterization equipment under illumination of a photovoltaic sample

Abstract

Equipment for electrical characterization under illumination of a photovoltaic sample The present description relates to equipment (200) for electrical characterization under illumination of a photovoltaic sample (100), comprising: - an IV measurement device (202) configured to carry out IV measurements on the photovoltaic sample; - a tip card (204) configured such that the tips are in contact with measurement electrodes of the photovoltaic sample during the IV measurements; - a microscope (206); - an illumination device (208); - a mechanical holding device (210) of the microscope and the illumination device, configured to allow movement of the microscope and the illumination device such that the microscope or the illumination device is arranged opposite the photovoltaic sample. Figure for the abstract: Fig. 2

Description

Title of the invention: Equipment for electrical characterization under illumination of a photovoltaic sample Technical field

[0001] The present description generally relates to the field of electrical characterization of a photovoltaic sample. Prior art

[0002] Several techniques have been developed to map the performance of a photovoltaic cell, i.e. to electrically characterize different regions of a photovoltaic cell.

[0003] Current-voltage measurements (also called IV measurements), in the dark or under illumination, are commonly used to evaluate the performance of photovoltaic cells or elements of these cells, and to understand the phenomena at the origin of certain limitations in the performance of the cells. Such an IV measurement applied to a photovoltaic cell consists of measuring the electric current delivered by the cell while applying an electric voltage to its terminals. This measurement makes it possible in particular to determine the short-circuit current, the open-circuit voltage, as well as the current and voltage at the maximum power of the photovoltaic cell.

[0004] The measurement method "Transfer Length Method", or TLM, also called "transfer length method", makes it possible to determine the conductivity of a layer of material and the contact resistivity between this layer of material and conductive measuring electrodes formed on this layer of material. In the field of photovoltaic cells, this method is implemented from a photovoltaic sample comprising at least one layer of absorber material (the same as that used to make the photovoltaic cell and which corresponds to a photovoltaic energy conversion material) on which several conductive measuring electrodes are arranged.The measuring electrodes are for example of elongated shape, arranged parallel to each other and spaced apart by a variable distance from each other, that is to say such that the distances between two neighboring or adjacent measuring electrodes are different from one pair of measuring electrodes to the other. These distances are called inter-electrode distances. Such a group of electrodes is called a TLM pattern, and a photovoltaic sample may comprise several TLM patterns each comprising for example electrodes whose geometric characteristics are different from one TLM pattern to another.

[0005] In the TLM method, IV measurements are performed for each of the different pairs of neighboring electrodes. It is then possible to determine the resistance values ​​for these different pairs of electrodes as a function of the inter-electrode distance of each of these pairs of electrodes, then to extract the values ​​of the electrical conductivity of the layer of absorber material and the contact resistance between this layer of absorber material and the measuring electrodes.

[0006] The implementation of the TLM method requires the production of conductive measuring electrodes on the surface of the sample to be characterized, these electrodes very often being metallic. This method is generally practiced in the dark. However, the photosensitive layers and contact resistivities of the characterized sample can be affected by the presence of light excitation. To achieve better accuracy, the electrical characterization of such samples should therefore be performed under illumination. However, there is no equipment specifically adapted to correctly characterize a photovoltaic sample under illumination by the TLM method.

[0007] Furthermore, there is no equipment specifically adapted to correctly characterize a photovoltaic sample under operating conditions, in terms of temperature, close to that of a solar cell, operating for example in a temperature range between 20°C and 100°C. Summary of the invention

[0008] There is therefore a need to propose new equipment suitable for electrically and correctly characterizing, under illumination and possibly in a given temperature range, a photovoltaic sample.

[0009] One embodiment overcomes all or part of the drawbacks of known solutions and proposes equipment for electrical characterization under illumination of a photovoltaic sample, comprising at least:

[0010] - an IV measurement device configured to perform IV measurements on the photovoltaic sample;

[0011] - a tip card configured such that the tips are in contact with measuring electrodes of the photovoltaic sample during IV measurements;

[0012] - a microscope;

[0013] - an illumination device;

[0014] - a device for mechanically holding the microscope and the illumination device, configured to allow movement of the microscope and the illumination device such that the microscope or the illumination device is arranged opposite the photovoltaic sample.

[0015] According to a particular embodiment, the mechanical holding device comprises at least one first articulated arm secured to the microscope, and at least one second articulated arm attached to the lighting device.

[0016] According to a particular embodiment, the first articulated arm is movable in rotation around a first axis and movable in translation parallel and perpendicular to the first axis.

[0017] According to a particular embodiment, the second articulated arm is movable in rotation around a second axis and movable in translation parallel and perpendicular to the second axis.

[0018] According to a particular embodiment, the equipment comprises one or more translation tables configured to ensure one or more of the translational movements of the first articulated arm and / or the second articulated arm.

[0019] According to a particular embodiment, the tips are configured such that they are in contact simultaneously with several pairs of measuring electrodes of the photovoltaic sample at least during the IV measurements.

[0020] According to a particular embodiment, the tip card comprises at least one opening opposite which ends of the tips are arranged and such that during the IV measurements, the photovoltaic sample is illuminated by the illumination device through the opening.

[0021] According to a particular embodiment, the tips are arranged such that, when the tips are in contact with measuring electrodes of the photovoltaic sample during IV measurements, the tips are positioned opposite the measuring electrodes.

[0022] According to a particular embodiment, the equipment further comprises a support configured to mechanically support the photovoltaic sample during IV measurements.

[0023] According to a particular embodiment, the support is motorized and configured to move relative to the probe card.

[0024] According to a particular embodiment, the support comprises at least one heating and / or cooling device configured to regulate the temperature of the photovoltaic sample when the latter is placed on the support.

[0025] According to a particular embodiment, the illumination device comprises at least one solar simulator.

[0026] According to a particular embodiment, the illumination device further comprises at least one control device configured to control at least the IV measurement device during the IV measurements.

[0027] According to a particular embodiment, the equipment further comprises at least one device for calculating electrical parameters of the photovoltaic sample by a TLM measurement method.

[0028] A method of electrical characterization under illumination is also proposed. of a photovoltaic sample, comprising at least the steps of:

[0029] - placing the photovoltaic sample in characterization equipment electric according to a particular embodiment;

[0030] - adjustment and control of the position of the photovoltaic sample by the mi electrical characterization equipment cross-section;

[0031] - contacting the tips of the tip card of the characterization equipment electrical against measuring electrodes of the photovoltaic sample;

[0032] - illumination of the photovoltaic sample by the illumination device of electrical characterization equipment;

[0033] - implementation of IV measurements on the photovoltaic sample. Brief description of the drawings

[0034] These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

[0035] [Fig.l] schematically represents an example of a photovoltaic sample intended to be electrically characterized by electrical characterization equipment under illumination according to a particular embodiment;

[0036] [Fig.2] represents an example of electrical characterization equipment under illumination of a photovoltaic sample according to a particular embodiment;

[0037] [Fig. 3] schematically represents an example of a device for mechanically holding electrical characterization equipment under illumination of a photovoltaic sample according to a particular embodiment;

[0038] [Fig.4] represents an example of a photovoltaic sample placed on a support of electrical characterization equipment under illumination of a photovoltaic sample according to a particular embodiment;

[0039] [Fig.5] represents an example of a probe card of a device for electrical characterization under illumination of a photovoltaic sample according to a particular embodiment;

[0040] [Fig.6] represents a part of an exemplary embodiment of a second articulated arm of a mechanical holding device for electrical characterization equipment under illumination of a photovoltaic sample according to a particular embodiment;

[0041] [Fig.7] represents an exemplary embodiment of a first articulated arm of a mechanical holding device for electrical characterization equipment under illumination of a photovoltaic sample according to a particular embodiment. Description of the embodiments

[0042] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different exemplary embodiments may have the same references and may have identical structural, dimensional and material properties.

[0043] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed.

[0044] Unless otherwise specified, when referring to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, this means that these two elements can be connected or be connected by means of one or more other elements.

[0045] In the various figures, the visible elements may not be represented on the same scale relative to each other to facilitate understanding of these figures.

[0046] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures in a normal position of use.

[0047] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0048] Throughout the description, the terms “neighboring” and “adjacent” are used interchangeably to describe two measuring electrodes arranged next to each other without a third measuring electrode being arranged between these two measuring electrodes.

[0049] Furthermore, throughout the description, the expression "electrical characterization equipment" is synonymous with the expression "electrical characterization device".

[0050] An example of a photovoltaic sample 100 comprising at least one layer of absorber material 112 and intended to be electrically characterized by electrical characterization equipment under illumination 200 is described below in connection with [Fig.l].

[0051] The sample 100 may comprise several layers of materials so that it is structurally close to or identical to a photovoltaic cell. In the example of [Fig.l], the sample 100 comprises layers similar to those of a heterojunction photovoltaic cell with passivated contacts.

[0052] In the example of [Fig.l], the sample 100 comprises a semiconductor substrate, comprising for example n-type crystalline silicon, or c-Si(n), and forming the layer of absorber material 112 of the sample 100. The thickness (dimension parallel to the Z axis shown in [Fig. 1]) of the layer 112 may be between 40 pm and 400 pm and may be for example equal to approximately 160 pm, and the electrical resistivity of the layer 112 is for example close to or equal to 1 Q.cm or between 0.1 Q.cm and 10 Q.cm.

[0053] The two main faces (front and rear faces parallel to the (X,Y) plane) of the layer 112 may be covered by layers 114 and 126 of intrinsic hydrogenated amorphous silicon (not intentionally doped), or a-Si:H(i), as is the case in the example of [Fig.l]. The thickness of each of the layers 114 and 126 is for example sufficient for each of them to form a passivation layer, and may be between 2 nm and 50 nm and is for example equal to 5 nm.

[0054] In the example of [Fig.l], the layer 126 located on the rear face side of the layer 112 is covered by a layer 116 of p-doped hydrogenated amorphous silicon, a-Si:H(p), and the layer 114 located on the front face side of the layer 112 is covered by a layer 118 of n-doped hydrogenated amorphous silicon, a-Si:H(n). These layers 114, 116, 118 and 126 can form a passivation of the material of the layer 112, make it photoconductive and create a selective contact for the charge carriers. The face of the layer 118 opposite that in contact with the layer 114 can form a first face 106 of the sample 100. The face of the layer 116 opposite that in contact with the layer 126 can form a second face 107 of the sample 100, corresponding to a rear face of the sample 100.

[0055] Alternatively, when the sample 100 comprises layers similar to those of a perovskite photovoltaic cell, the layer of absorber material 112 may comprise a material with a perovskite structure and have a thickness, for example, of between 200 nm and 5 μm. The passivation layers and the charge carrier selective layers may in this case be adapted to the perovskite material of the layer 112. It is also possible for the layer 112 to comprise another type of material, for example an amorphous semiconductor. Generally speaking, the absorber material of the sample 100 may correspond to a photosensitive, light-absorbing material, having conduction properties which vary under illumination thanks to the generation of charge carriers by this illumination.

[0056] In the example of [Fig.l], N pairs of adjacent measuring electrodes, referenced 108.1 to 108.4 in [Fig.l], are arranged on the first face 106 of the sample 100, with N being an integer greater than or equal to 2 and for example between 2 and 11. Each of these measuring electrodes comprises for example a transparent conductive oxide 120, or TCO (“Transparent Conductive Oxide” in English), corresponding for example to 1TTO (“Indium Tin Oxide” in English, or indium and tin oxide) and the thickness of which is for example equal to approximately 100 nm, and a metal layer 122 comprising for example silver and the thickness of which is for example example equal to approximately 10 qm, the transparent conductive oxide layer 120 being arranged between the metal layer 122 and the layer 118. The thickness of each measuring electrode (dimension parallel to the Z axis) is for example between 100 nm and 50 qm.

[0057] The number N of pairs of electrodes produced on the sample 100 may depend in particular on the precision desired for the electrical characterization of the sample 100. The greater the number N of pairs of electrodes used, the greater the precision of the extraction of the electrical parameters of the sample 100 carried out will be.

[0058] The N pairs of measuring electrodes form a TLM pattern of the sample 100. The sample 100 may comprise other TLM patterns formed by other measuring electrodes not visible in [Fig.l] but visible for example in [Fig.4]. In the sample 100, the different TLM patterns may be laterally isolated by implementing laser cutting.

[0059] Alternatively, the sample 100 may comprise layers of material different from those described for the example above, for example: absence of layers 116 and 118 and / or layers 114 and 126, replacement of layers 114 and 126 of a-Si:H(i) by different passivation layers such as for example chemical or thermal oxide layers, covering of layer 116 by a layer of TCO, replacement of the layers of amorphous semiconductor by nanocrystalline or microcrystalline or polycrystalline layers of semiconductor, other type of layer 112 semiconductor, etc.

[0060] In the example of [Fig.l], the sample 100 comprises 4 pairs of adjacent measuring electrodes referenced 108.1, 108.2, 108.3 and 108.4 (i.e. N = 4, N being the number of pairs of adjacent measuring electrodes used for the measurements). Each of the electrodes of the pairs of adjacent measuring electrodes may have a shape and dimensions identical to the other electrodes, for example a rectangular shape. Each electrode has for example a length L (dimension parallel to the X axis) of between a few tens of microns and a few mm, and a width IV (dimension parallel to the Y axis) of between a few mm and a few tens of mm. For example, the width IV of each of the measuring electrodes is equal to 15 mm, and the length L of each of the measuring electrodes is equal to 500 qm. Electrodes with a width of less than a millimeter are possible.

[0061] In the example described, the measuring electrodes are arranged next to each other parallel to their width IV (dimension parallel to the Y axis). In addition, the measuring electrodes can be arranged next to each other in such a way that each pair of electrodes formed by two adjacent electrodes are spaced apart by an inter-electrode distance which varies from one pair of electrodes to the other. Thus, the sample 100 can comprise at least 2 pairs of measuring electrodes whose inter-electrode distances are different from each other.

[0062] Each measuring electrode may be part of one or two adjacent pairs of measuring electrodes. In the example of [Fig.l], one of the measuring electrodes of the pair of electrodes 108.4 is also part of the pair of measuring electrodes 108.1, and the other of the measuring electrodes of the pair of electrodes 108.4 is also part of the pair of measuring electrodes 108.2. On the other hand, in the example of [Fig.l], none of the measuring electrodes of the pair of electrodes 108.3 is part of another pair of measuring electrodes.

[0063] In the example of [Fig.l], considering the inter-electrode distance d3 of the pair of electrodes 108.1, the inter-electrode distance d2 of the pair of electrodes 108.2, the inter-electrode distance d3 of the pair of electrodes 108.3, the inter-electrode distance d4 of the pair of electrodes 108.4, these distances are indexed such that d3 <d2< d3 < d4, c’est-à-dire telles que dj < dj+I, avec j nombre entier compris entre 1 et AM.

[0064] Between two adjacent electrodes of a pair of electrodes 108.i spaced by the distance di, the electrical resistance Rpair(di) measured at the terminals of these two electrodes has the expression: Rpair(di) = 2Rç+ (Rsf / W)*di

[0065] Rpair(di): resistance, in Ohm, measured between the two electrodes of the pair of adjacent measuring electrodes 108.i spaced from each other by the distance dt;

[0066] Rc: contact resistance, in Ohm, between an electrode of a pair of electrodes 108.i and the layer of absorber material 112;

[0067] Rsh: layer resistance, in Ohm / square.

[0068] Considering the example of [Fig.l], the assumption is made that the amorphous silicon layers 114, 116, 118, 126 have a very high transverse electrical resistivity between the two electrodes, which can be considered infinite. Considering further that the measuring electrodes are stacks of amorphous layers a-Si:H(i) 114, a-Si:H(n) 118, TCO 120 and metal 122 (for example silver) and that the current flows in the structure only in the crystalline silicon of the layer 112, it is possible to consider that:

[0069] - the contact resistance Rc includes the resistive contribution of the different layers of a-Si:H(i) 114, a-Si:H(n) 118, TCO 120 and metal 122 (silver in the example described above) as well as the contribution of the contact resistances c-Si(n) 112 / a-Si:H(i) 114 (contact resistance between layer 112 and layer 114 arranged on the front side of layer 112), a-Si:H(i) / a-Si:H(n) (contact resistance between layer 114 arranged on the front side of layer 112 and layer 118), a-Si:H(n) / TCO (contact resistance between layer 118 and TCO 120 of the measuring electrodes) and TCO / metal (contact resistance between TCO 120 and metal 122 of the measuring electrodes), and

[0070] - the layer resistance Rsh corresponds to that of layer 112.

[0071] In [Fig.l], the arrows designated by the reference 124 symbolically represent measuring tips intended to be applied to the electrodes when the resistances of the different pairs of electrodes are measured by a 4-wire (4W) method.

[0072] An example of embodiment of equipment 200 for electrical characterization of the sample 100 is described below in connection with [Fig.2].

[0073] The equipment 200 comprises an IV measurement device 202 configured to perform IV measurements on the sample 100. The device 202 may correspond to a “prober” type test equipment, such as those used to test wafers in the field of microelectronics. The device 202 may be automatic or semi-automatic, that is to say such that the IV measurements from one TLM pattern to another can be implemented without intervention, or little intervention, from the operator. For example, the device 202 can perform automated movement and contacting of the electrodes, as well as automated IV measurements between the different pairs of electrodes of the different TLM patterns.

[0074] The device 202 comprises one or more electrical measurement devices allowing the implementation of IV measurements on the sample 100. For example, this or these electrical measurement devices may correspond to a source and measurement unit (also called "Sourcemeter" in English, or SMU) making it possible to measure electrical resistances Rpaire(di) at the terminals of the pairs of electrodes of the sample 100, for example by 4-wire type IV measurements. The device 202 may also comprise other elements used for the implementation of these IV measurements, such as for example multiplexing cards making it possible to automate the IV measurements carried out between the different pairs of electrodes of the TLM patterns contacted by the probe card, etc.The IV measurements implemented may correspond to an injection of a measurement current through two adjacent measurement electrodes and a measurement of the voltage obtained between these electrodes, or an application of a voltage between two adjacent measurement electrodes and a measurement of the current flowing between these electrodes.

[0075] The equipment 200 also comprises a tip card 204 configured so that its tips are in contact with the measurement electrodes of the sample 100 during the IV measurements. This tip card 204 allows the electrical coupling between the measurement electrodes of the sample 100 and the electrical measurement equipment of the device 202 during the IV measurements implemented for the electrical characterization of the sample 100.

[0076] The equipment 200 further comprises a microscope 206, as well as an illumination device 208. The equipment 200 also comprises a mechanical holding device 210 mechanically supporting the microscope 206 and the device illumination device 208, and configured to move the microscope 206 and the illumination device 208 such that the microscope 206 or the illumination device 208 is disposed opposite the sample 100.

[0077] In an exemplary embodiment as shown in Figures 3, 6 and 7, the mechanical holding device 210 may comprise at least one first articulated arm 212 secured to the microscope 206, and at least one second articulated arm 214 secured to the illumination device 208. For example, the first articulated arm 212 may be movable in rotation about a first axis and movable in translation parallel and perpendicular to the first axis. In addition, the second articulated arm 214 may be movable in rotation about a second axis and movable in translation parallel and perpendicular to the second axis.

[0078] In the example of Figures 3 and 7, the first articulated arm 212 is rotatable about the first axis designated by the reference AA visible in [Fig. 3]. In this example, this rotation is achieved by a hinge 216 mechanically connecting the first articulated arm 212 to a fixed part of the mechanical holding device 210. In addition, a part of this first articulated arm 212 to which the microscope 206 is secured can be movable in translation parallel to the first axis AA, this translation movement being achieved for example by sliding parallel to the first axis AA of two parts 218, 220 of the first articulated arm 212 relative to each other.The part 218 of the first articulated arm 212 may correspond to a jack allowing, by sliding relative to the part 220, to approach the microscope 206 from a low working position, close to the sample 100, or to put it in a high position in order to allow movement of the microscope 206 while being distant from the sample 100. In addition, a translation table 219, visible in [Fig.7], may allow movement parallel to the axis AA of the microscope 206 relative to the part 218 to carry out fine adjustment of the distance between the microscope 206 and the sample 100, the adjustment of this distance being able to be ensured by a wheel.Finally, this first articulated arm 212 may comprise a translational movement device to which the microscope 206 is secured and making it possible to move the microscope 206 in the plane perpendicular to the axis AA, that is to say in a plane parallel to the main plane of the sample 100 when the latter is positioned under the microscope 206. In the example of [Fig.7], this translational movement in the plane perpendicular to the axis AA is ensured by two translation tables 240, 242 oriented along axes perpendicular to each other and perpendicular to the axis AA.

[0079] The rotational movement of the first articulated arm 212 around the first axis AA can make it possible to position the microscope 206 above the sample 100 before the measurements IV, and to move the microscope 206 away from the sample 100 when the latter is illuminated by the illumination device 208 during measurements IV. The translational movement of the two parts 218, 220 of the first articulated arm 212 relative to each other and that provided by the translation table 219 can make it possible, when the microscope 206 is arranged above the sample 100, to approach the microscope 206 and to adjust the distance between the objective of the microscope 206 and the sample 100. The movement of the microscope 206 in the plane perpendicular to the axis AA can be used to arrange the microscope 206 opposite the desired region of the sample 100 and / or the desired tips of the card 204, for example during the initial positioning of the tips of the card 204 against the measuring electrodes of the sample 100.

[0080] In the example of [Fig. 3], the second articulated arm 214 is movable in rotation around the second axis designated by the reference BB, this rotation being carried out between a first part 222 of the second articulated arm 214 and the fixed part of the mechanical holding device 210. In addition, a second part 224 of the second articulated arm 214 is movable in translation parallel to the second axis BB, this translation movement being carried out for example by the sliding of two elements relative to each other of the second part 224 of the second articulated arm 214 by means of a translation table. In addition, as can be seen in [Fig.6] which represents a part of the second articulated arm 214, the latter comprises two translation tables 215, 217 oriented along axes perpendicular to each other and perpendicular to the axis BB and allowing a movement, in the plane perpendicular to the axis BB, of the second part 224 relative to the first part 222 of the second articulated arm 214, and therefore a translation movement between the first part 222 of the second articulated arm 214 and the illumination device 208. The translation axes of the tables 215, 217 can advantageously correspond to the main axes of the device 202.

[0081] The rotational movement of the second articulated arm 214 around the second axis BB can make it possible to position the illumination device 208 above the sample 100 during the IV measurements, and to move the illumination device 208 away from the sample 100 when the microscope 206 is positioned above the sample 100. The translational movement, in the plane perpendicular to the axis BB, of the second part 224 relative to the first part 222 of the second articulated arm 214 makes it possible to adjust, in this plane, the position of the illumination device 208 above the sample 100.The translational movement of the two elements of the second part 224 of the second articulated arm 214 relative to each other can make it possible, when the illumination device 208 is arranged above the sample 100, to adjust the distance between the illumination device 208 and the sample 100, this distance being able to be a few centimeters, and for example of the order of 20 cm.

[0082] According to an exemplary embodiment, the illumination device 208 may correspond to a multi-wavelength solar simulator for illuminating the sample 100 with different light spectra, configured to emit wavelengths for example between 400 nm and 1100 nm. This solar simulator may comprise for example independently controllable LED light sources in order to reproduce specific light spectra. The intensity of the light emitted by the illumination device 208 may be variable and for example between 0 and 1 sun (or sun, 1 sun corresponding to 1000 W / m2). For example, the illumination device 208 may be configured to emit light corresponding to a standardized solar spectrum of type AM 1.5 corresponding to 1 sun.

[0083] According to an exemplary embodiment, the illumination device 208 can be positioned in an enclosure making it possible to apply darkness, i.e. to isolate the sample 100 from the ambient brightness in the environment of the measuring equipment.

[0084] In the exemplary embodiment described, the equipment 202 also comprises a support 226, also called a “chuck” in English, configured to mechanically support the sample 100 in particular during IV measurements. [Fig. 4] represents an exemplary embodiment of the support 226 on which the sample 100 is arranged. In the configuration visible in [Fig. 4], the tip card 204 is not arranged above the sample 100. In addition, in [Fig. 4], the visible sample 100 corresponds to a wafer having 8 TLM patterns and resting on the support 226.

[0085] According to an exemplary embodiment, the support 226 can be motorized and configured to move, with an accuracy of a few microns, relative to the tip card 204 when the latter is positioned to electrically contact the measurement electrodes of the sample 100.

[0086] Furthermore, in a particular embodiment, the support 226 may comprise a heating and / or cooling device configured to regulate the temperature of the sample 100 when the latter is placed on the support 226. This heating and / or cooling device may comprise a circulation cryostat with air cooling, making it possible to regulate the temperature of the sample 100 when it is for example between ambient temperature and 200°C. This device may also be supplemented by an air / water circulation cooler making it possible to cool elements of the measuring equipment, for example used when the temperature of the sample 100 is greater than 150°C.

[0087] [Fig. 5] represents an exemplary embodiment of the probe card 204. In this example, the card 204 is produced from a printed circuit 228 on which connectors 230 are each connected to at least one of the probes 232 of the card 204.

[0088] In a particular configuration, the tip card 204 may comprise at least one opening 234 opposite which ends of the tips 232 are arranged and such that during the IV measurements, the sample 100 is illuminated by the device illumination 208 through this opening 234. Furthermore, according to a particular embodiment corresponding to that visible in [Fig.5], the tips 232 can be arranged symmetrically with respect to an axis parallel to the largest dimension of the opening 234 and each extend in a direction perpendicular to this axis. When the tips 232 are in contact with measuring electrodes 108.1 - 108.4 of the photovoltaic sample 100 during the IV measurements, the tips 232 are positioned opposite the measuring electrodes. An advantage of such an arrangement of the tips 232 is that their shadow is cast on the electrodes and does not induce, on the absorber, additional shading to that due to the electrodes. The card 204 shown in [Fig.5] corresponds to an example of such a particular embodiment.

[0089] The number of tips 232 of the card 204 can be chosen as a function of the number of measuring electrodes of the sample 100 intended to be contacted by the tips 232. Similarly, the distances between the tips 232 can be chosen as a function of the distances between the measuring electrodes of the sample 100 intended to be contacted by the tips 232. In the exemplary embodiment shown in [Fig. 5], the card 204 comprises 12 pairs of tips 232. For example, the tips 232 can comprise an alloy of tungsten and rhenium. In addition, the tips 232 can be arranged such that during IV measurements, they extend in a direction parallel to the electrodes of the sample 100 in order to limit the shadowing brought on the sample 100 by the tips 232.

[0090] In a particular configuration, the tips may be configured to be in contact simultaneously with several pairs of measurement electrodes of the photovoltaic sample 100. For example, it is possible for the card 204 to be such that, during a measurement, all the electrodes of a TLM pattern of the sample 100 are contacted by the tips 232.

[0091] The equipment 200 may comprise at least one control device, for example a computer equipped with software configured to control the various elements and devices of the equipment 200. This control circuit may for example perform the following functions: control of the electrical measurement equipment, management of the movements of the support 226, control of the illumination device 208, control of the temperature regulation of the support 226, recording of the results of electrical measurements, etc.

[0092] The equipment 200 may also comprise at least one device for calculating electrical parameters of the sample 100 by a TLM measurement method. For example, this calculation device can determine, from the results of the IV measurements implemented on the different measurement electrodes of the sample 100, resistance values ​​for the different pairs of measurement electrodes as a function of the inter-electrode distance of each of the pairs of electrodes, then extract the values of the electrical conductivity of the layer of absorber material of the sample 100 and of the contact resistance between this layer of absorber material and the measuring electrodes of the sample 100.

[0093] With the equipment 200, it is possible to implement a method of electrical characterization of the sample 100 as described below.

[0094] The sample 100 is first placed by an operator in the equipment 200, and more particularly on the support 226.

[0095] The position of the sample 100 on the support 226 can then be adjusted and checked using the microscope 206 which is then arranged opposite the sample 100. The correct positioning of the measuring electrodes of the sample 100 against the tips 232 can also be checked by the microscope 206. The adjustment of the position of the sample 100 can be carried out either manually or by means of the motorization of the support 226.

[0096] The tips 232 of the card 204 are brought into contact against measuring electrodes of the sample 100.

[0097] The microscope 206 is then removed and moved away from the sample 100, and then the illumination device 208 is positioned above the TLM pattern of the sample 100 contacted by the card 204.

[0098] The sample 100 is then illuminated by the illumination device 208, and the IV measurements under illumination are then carried out. The implementation of the IV measurements makes it possible to measure the IV characteristic between each pair of adjacent electrodes of the TLM pattern of the sample 100 contacted by the tips 234 of the card 204. The measurements implemented may be, for example, 4-wire type measurements.

[0099] In a particular implementation, these IV measurements may be repeated for different light spectra and / or different light intensities.

[0100] The support 226 can then be moved automatically by the control device of the equipment 200 so that the measurement electrodes of another TLM pattern are contacted by the tips 232 of the card 204, then new IV measurements can be carried out, then the electrodes of the sample 100 are moved away from the tips 232. These steps can be repeated for the different TLM patterns present on the sample 100.

[0101] From the measurement results, the calculation device can determine the electrical resistance of each of the pairs of measurement electrodes of the TLM pattern, then extract for example the values ​​of the layer resistance of the layer of absorber material of the sample 100 and of the contact resistance between this layer of absorber material and the measurement electrodes of the sample 100.

[0102] In a particular application, the equipment 200 can be used to characterize, for example, photovoltaic structures with crystalline silicon heterojunctions, with passivated and high-performance contacts, combining for example thin layers of transparent conductive oxide (TCO) and hydrogenated amorphous silicon (a-Si:H) with a crystalline silicon absorber. The equipment 200 can in particular be used to determine the resistive losses obtained in photovoltaic cells in operation, that is to say under illumination and temperature, made with the absorber material thus characterized. The equipment 200 can be used to produce maps of the electrical properties of an absorber material on a substrate, or wafer, as shown in [Fig.4],

[0103] Various exemplary embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art. In particular, the electrical measurements implemented by the equipment 200 may be different from those described above.

[0104] Finally, the practical implementation of the embodiments and variants described is within the reach of those skilled in the art from the functional indications given above.

Claims

Claims

1. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100), comprising at least: - an IV measuring device (202) configured to carry out IV measurements on the photovoltaic sample (100); - a tip card (204) configured such that the tips (232) are in contact with measuring electrodes (108.1 -108.4) of the photovoltaic sample (100) during the IV measurements; - a microscope (206); - an illumination device (208); - a mechanical holding device (210) for the microscope (206) and the illumination device (208), configured to allow movement of the microscope (206) and the illumination device (208) such that the microscope (206) or the illumination device (208) is arranged opposite the photovoltaic sample (100).

2. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to claim 1, in which the mechanical holding device (210) comprises at least one first articulated arm (212) secured to the microscope (206), and at least one second articulated arm (214) secured to the illumination device (208).

3. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to claim 2, in which the first articulated arm (212) is movable in rotation around a first axis and movable in translation parallel and perpendicular to the first axis.

4. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to one of claims 2 or 3, in which the second articulated arm (214) is movable in rotation around a second axis and movable in translation parallel and perpendicular to the second axis.

5. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to one of claims 3 or 4, comprising one or more translation tables configured for ensure one or more of the translational movements of the first articulated arm (212) and / or the second articulated arm (214).

6. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to one of the preceding claims, in which the tips (232) are configured such that they are in contact simultaneously with several pairs of measuring electrodes (108.1 - 108.4) of the photovoltaic sample (100) at least during the IV measurements.

7. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to one of the preceding claims, in which the tip card (204) comprises at least one opening (234) opposite which ends of the tips (232) are arranged and such that during the IV measurements, the photovoltaic sample (100) is illuminated by the illumination device (208) through the opening (234).

8. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to claim 7, in which the tips (232) are arranged such that, when the tips (232) are in contact with measuring electrodes (108.1 - 108.4) of the photovoltaic sample (100) during IV measurements, the tips (232) are positioned opposite the measuring electrodes (108.1 - 108.4).

9. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to one of the preceding claims, further comprising a support (226) configured to mechanically support the photovoltaic sample (100) during IV measurements.

10. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to claim 9, in which the support (226) is motorized and configured to move relative to the probe card (204).

11. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to one of claims 9 or 10, in which the support (226) comprises at least one heating and / or cooling device configured to regulate the temperature of the photovoltaic sample (100) when the latter is arranged on the support (226).

12. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to one of the preceding claims preceding, wherein the IV measuring device (202) comprises at least one source and measuring unit.

13. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to one of the preceding claims, in which the illumination device (208) comprises at least one solar simulator.

14. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to one of the preceding claims, further comprising at least one control device configured to control at least the IV measurement device (202) during the IV measurements.

15. Equipment (200) for electrical characterization under illumination of a photovoltaic sample (100) according to one of the preceding claims, further comprising at least one device for calculating electrical parameters of the photovoltaic sample (100) by a TLM measurement method.

16. Method for electrical characterization under illumination of a photovoltaic sample (100), comprising at least the steps of: - placing the photovoltaic sample (100) in an electrical characterization equipment (200) according to one of the preceding claims; - adjusting and controlling the position of the photovoltaic sample (100) by the microscope (206) of the electrical characterization equipment (200); - bringing the tips (232) of the tip card (204) of the electrical characterization equipment (200) into contact with measuring electrodes (108.1 - 108.4) of the photovoltaic sample (100); - illuminating the photovoltaic sample (100) by the illumination device (208) of the electrical characterization equipment (200); - implementation of IV measurements on the photovoltaic sample (100).

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