DE102010018595A1 - Process for producing a compound semiconductor layer - Google Patents

Abstract

Method for producing a I-III-VI compound semiconductor layer (80), in which a substrate (50) is provided (10, 12) with a coating (63) which has a metallic precursor layer (57) and heats the coating (63) and is maintained at temperatures of at least 350 ° C. for the duration of a process time (16) and the metallic precursor layer (57) is converted (16) into the compound semiconductor layer (80) in the presence of a chalcogen (58; 72), wherein between a predominant portion (15a) of a free surface (15a, 15b; 25) of the coating (63) and a cover (60; 70) during the process time at least a flat contact is provided (14; 24).

Description

The present invention relates to a method for producing a compound semiconductor layer according to the preamble of claim 1.

An environmentally friendly and low-cost energy generation is a central problem of today. One solution for this problem is photovoltaic power generation from sunlight using solar cells or solar modules. The cost of power generation is the lower, the greater the conversion efficiency of the solar modules and the lower their production costs. Against this background, so-called thin-film solar modules are a promising solution, since they can be manufactured with low material and energy expenditure and also have a good conversion efficiency, ie. H. high efficiencies allow. In particular, thin-film solar modules based on I-III-VI compound semiconductors have proven themselves. These include, for example, compound semiconductors of a copper indium selenide (CIS) or a copper indium gallium selenide (CIGS).

Compound semiconductor layers can be prepared in various ways, for example by co-vapor deposition of the elements involved. Another production possibility are so-called deposition-reaction processes, in which first a metallic precursor layer is deposited and subsequently converted with chalcogens into a compound semiconductor.

A deposition-reaction process in which the metallic precursor layer is thermally converted to the compound semiconductor layer in a rapid process is disclosed in the document EP 0 662 247 B1 described. In the process, a substrate with metallic precursor layer and chalcogen layer is rapidly heated in a small process space. A suitable for mass production flow method is not disclosed.

In the international patent applications WO 2009/033674 A2 and WO 2009/135685 A2 are continuous process for the thermal conversion of metallic precursor layers on substrates in semiconducting layers specified. In the teaching of WO 2009/033674 A2, chalcogenes in quantities up to twice the amounts which correspond to the exact stoichiometric proportion of the respective chalcogen to the compound semiconductor layer formed are required for the formation of the compound semiconductor layer. This represents a cost of materials, which is reflected in the costs of the proceedings. From WO 2009/135685 A2 it is known to provide the article with a process hood in the annealing of an article in a treatment chamber and thereby to reduce losses in evaporating materials. This requires elaborately designed treatment chambers, or furnaces, in which one or more process hoods are movably arranged.

Against this background, the object of the present invention is to provide a cost-effective method for producing an I-III-VI compound semiconductor layer.

This object is achieved by a method having the features of claim 1.

Advantageous developments are the subject of dependent claims.

The inventive method provides that a substrate is provided with a coating which has a metallic precursor layer. This coating is heated and maintained at temperatures of at least 350 ° C for the duration of a process time. Here, the metallic precursor layer is converted into an I-III-VI compound semiconductor layer in the presence of a chalcogen. During the process time, a surface contact between a predominant portion of a free surface of the coating and a cover is at least temporarily provided.

The provision of a planar contact is to be understood in that it is ensured that at least at times during the process time there is a surface contact between the predominant portion of the free surface of the coating and the cover.

In the present case, the free surface of the coating means those surface portions of the coating which are not already directly covered without the cover in any way. For example, surface portions of the coating may be directly covered by the substrate or a back contact disposed on the substrate. On the other hand, a hood which does not contact the coating or only in places does not cover any contacted coating parts, if any, indirectly.

The flat contact according to the present invention is not necessarily formed from a continuous contact surface. Accordingly, the majority of the free surface, which is at least temporarily in planar contact with the cover, is not necessarily a contiguous surface. The cover can thus basically be formed of several, not necessarily interconnected individual covers.

An I-III-VI compound semiconductor layer is understood herein to mean a layer of a compound semiconductor which consists of elements of group IB of the periodic table, for example copper, of elements of group IIIA of the periodic table, for example aluminum, gallium or indium, and at least one chalcogen from the group VIA of the Periodic Table, for example sulfur, selenium or tellurium.

The fact that the coating is kept at temperatures of at least 350 ° C is not to be understood as meaning that the coating is heated to a certain temperature and held at this particular temperature during the entire process time. Instead, the invention provides that the coating during the process time any temperatures greater than or equal to 350 ° C. During the process time, the temperature of the coating may vary, but it is always at least 350 ° C during the process time.

The process time may in principle be interrupted by phases in which the temperature of the coating is less than 350 ° C. The process time in such a case is composed of the sum of those times in which the temperature of the coating is greater than or equal to 350 ° C.

A coating in the sense of the present invention can consist solely of a metallic precursor layer, for example a layer comprising the metals copper, gallium and indium, or have further constituents, such as, for example, a chalcogen layer which is deposited on the metallic precursor layer. In the present case, the term coating thus comprises all layers arranged on the substrate and the metallic back contact layer optionally provided there. The coating consists after partial conversion of the metallic precursor layer, for example, partly from a compound semiconductor. The compound semiconductor layer present after complete conversion likewise represents a coating in the present sense.

The process according to the invention makes it possible to produce the compound semiconductor layer with low consumption of chalcogens. This is due to the fact that in the areas of the free surface of the coating which are in contact with the cover, a loss of vaporized chalcogens is virtually ruled out. It has been found that despite the contact of the cover with the free surface of the coating, good quality compound semiconductor layers can be produced. Surprisingly, it has further been found that the cover can be easily separated from the coating after the conversion of the metallic precursor layer, without damaging the compound semiconductor layer produced. The inventive method is therefore universally applicable and not limited to those applications in which the cover can remain on the coating. An embodiment of the invention therefore provides that after the conversion of the metallic precursor layer, the cover is separated from the coating.

Since, in the method according to the invention, areas of the surface of the coating covered by the cover are in direct contact with the cover, no voids or at most very small voids are formed between the cover and these areas of the surface of the coating. There are thus no cavities in which unwanted gases such as oxygen or water vapor could be stored to a relevant extent during the conversion process. The contact between the free surface of the coating and the cover can therefore be formed inexpensively under atmospheric environmental conditions, for example, in which the cover is placed on the coating before it is introduced into an oven. In this way, the expense for the production of the compound semiconductor layer can be additionally reduced, since complex devices for handling process hoods or the like within the furnace can be omitted. However, in principle, the cover can first be brought into contact with the free surface of the coating in an oven or coating chamber. Appropriate devices would then be provided.

In principle, in the method according to the invention, any substrates can be used which are not adversely affected during the implementation of the method by heat influence or chemical reactions. In addition to glass substrates, for example, bands made of metal can be used.

Advantageously, the substrate is provided with a back contact. For example, a metal layer may be provided as a back contact on a glass substrate, in particular a molybdenum layer. The back contact is preferably divided by structuring into a plurality of strips, whereby a series connection of different solar cell elements of the finished solar module can be realized. The said molybdenum coating does not form part of the metallic Previous layer or coating in the context of the present invention.

The metallic precursor layer can contain, for example, copper, indium and gallium and can be applied using technologies known per se, for example by sputtering. The metallic precursor layer can basically consist of several metallic layers, for example, a copper and gallium-containing layer can first be provided and applied to this an indium layer. Furthermore, the metallic precursor layer may be composed of a plurality of similar sublayers, for example a plurality of layers containing copper and gallium. In addition, repetitive layer sequences can be provided. In addition, the metallic precursor layer Chalkogene, z. In the form of chalcogenides.

In a particularly preferred embodiment of the invention, the metallic precursor layer is converted into a CIS or CIGS compound semiconductor layer.

An embodiment variant of the invention provides for a process time which is shorter than 1200 s, preferably shorter than 600 s. Particularly preferably, the process time has a duration between 150 s and 500 s.

In an advantageous embodiment variant of the invention, a cover is used, which is made of a material having a comparatively high thermal conductivity, for example of graphite or another carbon modification or silicon carbide. In this way, temperature differences extending over the surfaces of the coatings can be better compensated. It has been found that compound semiconductor layers with improved homogeneity can be produced in this way. Since homogeneity is essential to the quality of a compound semiconductor layer, compound semiconductor layers of improved quality can be produced in the manner described.

In one embodiment variant of the method according to the invention, before the heating of the coating, a chalcogen layer having at least one chalcogen is deposited on the metallic precursor layer. The planar contact is subsequently provided substantially between the chalcogen layer and the cover. For this purpose, the surface contact is preferably formed before the heating of the coating. The deposition of the chalcogen layer having at least one chalcogen is advantageously carried out by means of a physical vapor phase deposition at atmospheric pressure (APPVD). Particularly preferably, the chalcogen deposition takes place in a continuous process. In particular, sulfur or selenium can be deposited. The deposited chalcogen layer serves, optionally together with chalcogens from other sources, as chalcogen source for the conversion of the metallic precursor layer into the compound semiconductor layer.

In a further development of the method according to the invention, a cover is used which, on its side facing the coating, is coated at least in sections with one or more chalcogens, preferably with selenium. Such a chalcogen coating of the cover may be used as a single or additional chalcogen source for the conversion of the metallic precursor layer into the compound semiconductor layer. In particular, it can be provided as an alternative or in addition to a chalcogen layer deposited on the metallic precursor layer. The coating of the cover with one or more chalcogenes, in turn, can advantageously be carried out by means of a physical vapor deposition at atmospheric pressure.

In a preferred embodiment of the invention, the surface contact between the vast majority of the free surface of the coating and the cover is provided during the entire process time. In all embodiments of the invention, the flat contact described can also be provided outside the process time.

In an advantageous embodiment variant of the invention, the coating is arranged together with the cover at least during the process time in a protective gas atmosphere, preferably in a nitrogen or inert gas having atmosphere. Preferably, the coating and cover are already arranged in the protective gas atmosphere during a heating phase preceding the process time, and these are maintained until the coating cools to an uncritical temperature. The arrangement of coating and cover in a protective gas atmosphere serves inter alia to ensure the lowest possible oxygen partial pressure during a thermal treatment of the coating, in particular during their conversion to a compound semiconductor layer, since an oxygen supply can trigger unwanted chemical reactions. Thus, solar cells or solar cell modules made from compound semiconductor layers made under the presence of oxygen have been found to have a reduced efficiency. Depending on the application, the inert gas atmosphere continue to serve the Wassersstoffpartialdruck, or partial pressures of hydrogen-containing gases to keep as low as possible in the process atmosphere, so that the formation of toxic gases, such as selenium in the use of selenium as chalcogen, is largely avoided.

In practice, it has been found useful to provide the chalcogens in quantities exceeding 0% to 90% over their respective stoichiometric amount of the compound semiconductor layer formed, preferably by 40% to 80%, during the conversion of the metallic precursor layer into the compound semiconductor layer.

If the substrate is provided with a back contact, for example by providing a metal layer as a back contact on a glass substrate, the formation of backside metal chalcogenides can be controlled by the range of chalcogens. For example, it has been found that when using a molybdenum layer as back contact on the substrate and using selenium as chalcogen, the thickness of the molybdenum selenide layer formed can be influenced by the amount of selenium offered. This can be used, for example, to optimize a solar cell manufactured using the compound semiconductor layer produced, or a solar module.

In a further development of the method according to the invention, a plate is used as cover. Under a plate is to be understood a flat structure whose extension in length and width is a multiple of its thickness. Preferably, a silicon carbide plate, and more preferably a graphite plate or a carbon fiber reinforced carbon plate, is used since these materials have good heat conductivity. The use of a plate with good thermal conductivity makes it possible to compensate for any temperature inhomogeneities within a furnace, whereby the homogeneity of the prepared compound semiconductor layer can be improved. Thus, plates with good thermal conductivity enable the production of large-area, homogeneous compound semiconductor layers. In addition, contamination of the prepared compound semiconductor layer by impurities originating from the furnace can be reduced by extensive contact of the plate with the coating. In addition to those mentioned, a glass plate, a quartz plate or a sapphire plate can also be used. Plates of the type described can readily be separated from the coating after conversion of the metallic precursor layer into the compound semiconductor layer. Measures to facilitate the separation process are not required.

The rigidity of the plate is basically of no importance for carrying out the method according to the invention. It may be, for example, a plate with high rigidity or a flexible mat or foil. If the plate is assigned a supporting function during the practical implementation of the method according to the invention, its rigidity must be selected accordingly.

A variant of the method according to the invention provides that the surface contact between the predominant portion of the free surface of the coating and the cover is provided before the coating is introduced into an oven for the purpose of converting the metallic precursor layer into the compound semiconductor layer.

In a further embodiment variant of the invention, the cover used is a wall of a furnace in which the coating is heated. This wall can be formed, for example, by a plate, in particular a silicon carbide plate or graphite plate or a plate made of carbon fiber reinforced carbon.

The surface contact between the predominant portion of the free surface of the coating and the wall can be prepared, for example, by the coating is moved up after insertion into the furnace to the wall of the furnace. The oven would be equipped in this case with appropriate appropriate devices.

It is obvious that other suitable furnace components can be used as a cover instead of the wall of the furnace. For example, a shield plate provided in the furnace can be used as a cover.

A stack formed from substrate, coating and cover, as which in particular a plate may be provided, can in principle be arranged arbitrarily in space. For example, a stack of planar components may be arranged such that the surfaces extend substantially horizontally or vertically. In an arrangement with a substantially horizontal extent of the planar stack constituents, the coating and the cover can be arranged either on the top side of the substrate or on the underside of the substrate. In the case of an arrangement on the underside of the substrate, it must be taken into consideration that the cover assumes a supporting function, so that its rigidity or stability must be selected accordingly.

It has been found that the coating can be heated homogeneously by heating the cover which is in contact with the coating in the planar contact in a targeted manner for a predetermined time. The targeted heating can for example be realized by the cover plate is irradiated with short-wave electromagnetic radiation of a wavelength which is absorbed by the cover plate to a large extent. The material used for the production of the cover plate and the wavelength of the electromagnetic radiation used are to be coordinated accordingly. Furthermore, when choosing the material for the cover plate to take into account that this has a good heat conduction. In the targeted heat input by means of the electromagnetic radiation resulting inhomogeneities in the heating of the cover are so homogenized and heated the coating in a homogeneous manner. This enables the production of large area compound semiconductor layers of good homogeneity.

In a preferred embodiment variant of the method according to the invention, the metallic precursor layer is converted into the compound semiconductor layer at a process pressure in the vicinity of the atmospheric ambient pressure. For example, the process pressure may deviate from the atmospheric pressure due to flows in the process environment. In no case, in this embodiment variant of the invention, the process environment is evacuated and the process pressure is not more than 50 mbar lower than the atmospheric ambient pressure. This makes it possible to dispense with time-consuming and expensive vacuum systems.

In an advantageous embodiment variant of the invention, the coating is heated in a continuous furnace. This makes it possible to produce compound semiconductor layers, particularly in connection with production of solar cells or solar modules, on an industrial scale. In principle, however, the heating can also take place in a so-called batch oven designed for batch operation.

Preferably, a segmented continuous furnace is used, in which the coating in different segments of the continuous furnace can be brought to different temperatures. In this case, a flat substrate, a planar coating and a plate are particularly preferably used as cover and the resulting stack is oriented such that the surfaces extend substantially horizontally. In this orientation, the stack is then transported through the segmented continuous furnace. This transport can be done in particular step by step. It has been found that in the described embodiment in the continuous furnace prevailing gas flows relative to the coating at those locations at which a flat contact between the free surface of the coating and the cover is provided, have almost no detrimental effect on the formed compound semiconductor layer. If glass substrates are used, it may be advantageous to arrange the stack during transport through the continuous furnace on an additional support plate, so that even in the case of glass breakage, the stack is transported out of the continuous furnace.

In another embodiment variant of the invention, the coating and the substrate are arranged on the cover and the cover is used as a carrier for a stack formed from coating and substrate. The stack can then be transported through the continuous furnace on the cover acting as a carrier. Since the cover in this case has a supporting function, their rigidity or stability must be interpreted accordingly. In addition, a protective plate may be disposed on the side of the substrate which is on top of the described arrangement. As a result, further stabilization can be achieved.

In an advantageous embodiment variant of the method according to the invention, the cover is heated before the flat contact is formed between it and the predominant portion of the free surface of the coating. If the flat contact is provided only for a short time, in this way the coating can be heated to a higher temperature than the substrate by a heat transfer from the cover to the coating. As a result, inexpensive substrates can be used despite high temperatures of the coating, which are not suitable for the high temperatures. In this advantageous embodiment variant, the cover is preferably heated to a temperature of at least 400 ° C, more preferably to a value of at least 600 ° C and most preferably to a value of at least 640 ° C.

Furthermore, the invention will be explained in more detail with reference to figures. Where appropriate, elements having equivalent effect are provided with like reference numerals. Show it:

1 Schematic representation of a first embodiment of the method according to the invention

2 Exemplary schematic representation of a substrate and arranged thereon Layers before the conversion of the metallic precursor layer in the compound semiconductor layer with the method according to the embodiment of 1

3 Schematic representation of a second embodiment of the method according to the invention

4 Exemplary, schematic illustration of laying a selenium coated graphite plate according to the method of the embodiment of 3

5 Example of one with the method according to the 1 or the 3 prepared compound semiconductor layer after removing the cover

6 Schematic representation of the heating of the coating in a segmented continuous furnace

7 Solar cell according to the prior art

8th Schematic partial representation of a further embodiment of the method according to the invention

1 shows a schematic diagram of a first embodiment of the method according to the invention. This will be explained below with reference to 2 which illustrates by way of example a schematic representation of a substrate and layers arranged thereon before the conversion of the metallic precursor layer into the compound semiconductor layer with the in 1 shows shown method. According to the method 1 is first on one with a back contact 52 provided glass substrate 50 a metallic precursor layer 57 sputtered. The on the glass substrate 50 provided back contact 52 can be formed for example by sputtering a molybdenum layer. The metallic precursor layer 57 is composed of a copper gallium layer 54 and an indium layer 56 ,

Furthermore, by means of a physical vapor deposition at atmospheric pressure (APPVD) a selenium layer 58 on the metallic precursor layer 57 educated 12 , Obviously, other chalcogenes can be used instead of selenium. The selenium layer 58 forms in the present embodiment, together with the metallic precursor layer 57 a coating 63 out. Furthermore, as a cover, a graphite plate 60 on the selenium layer 58 hung up 14 , Before this hang up 14 the graphite plate 60 is the selenium layer 58 , and with it the coating 63 , uncovered at the top. In addition, only the side surfaces of the coating 63 uncovered, leaving the top of the selenium layer 58 the overwhelming share 15a a free surface 15a . 15b the coating 63 represents. By far the majority 15a the free surface 15a . 15b the coating 63 is by hanging up 14 the graphite plate 60 with the graphite plate 60 brought into contact with each other. Only the lateral free surfaces 15b the coating 63 stay uncovered and thus contactless. During a subsequent heating and holding 16 the coating 63 to at least 350 ° C and conversion of the metallic precursor layer 57 In a compound semiconductor layer is thus a surface contact between a predominant share 15a the free surface 15a . 15b the coating 63 and the covering graphite plate 60 provided. This surface contact is provided throughout the process time and beyond, particularly during the heating process of the coating to 350 ° C. 2 shows as it were a snapshot after hanging up 14 the graphite plate and before the coating reaches a temperature of 350 ° C.

After the conversion 16 the metallic precursor layer 57 into a compound semiconductor layer becomes the graphite plate 60 from the coating 63 which now at least partially consists of a compound semiconductor layer, separated 18 ,

3 shows a schematic representation of a second embodiment of the method according to the invention. This is different from the one of 1 in that no selenium layer on the metallic precursor layer 57 is deposited. Instead, as in 4 indicated schematically, a graphite plate 70 which on its side facing the coating with a selenium layer 72 is provided, placed on the coating and thereby provided a surface contact with the coating 24 , In the in the 3 and 4 illustrated embodiment, the coating is solely by the metallic precursor layer 57 educated. Their uncovered surface thus provides a free surface 25 the coating. The with the selenium layer 72 provided graphite plate 70 , will be like in 4 through the arrows 24 indicated on the metallic precursor layer 57 applied and thereby the areal contact between in this embodiment by the metallic precursor layer 57 formed coating and the selenium coated graphite plate used as cover 70 . 72 provided.

This is followed by heating again 16 and hold 16 the coating to at least 350 ° C and converting the metallic precursor layer 57 in the compound semiconductor layer at. Below is the graphite plate 70 removed from the now at least partially converted coating 18 ,

The embodiments of the 1 and 3 can be combined so that first a chalcogen layer on the metallic precursor layer 57 is deposited, so the coating 63 as in the case of 2 a selenium stratification 58 and, in addition, a cover provided with a selenium coating, for example, those with a selenium coating 72 provided graphite plate 70 out 4 , is placed on the coating and in this way a flat contact between the free surface of the coating and the cover is provided. Obviously, other chalcogenes can also be used as selenium.

In particular, a different chalcogen can be deposited on the metallic precursor layer than the subsequently applied cover. When using the graphite plate 70 out 4 For example, it could be coated with selenium while depositing a sulfur layer prior to placing the cover on the metallic precursor layer. In principle, however, these layers can also consist of the same chalcogen.

5 shows a schematic representation of an example of a compound semiconductor layer, as with the method according to the 1 or 3 can be produced. 5 illustrates the facts after the in the 1 and 3 intended separating 18 the graphite plate 60 , respectively. 70 , from the coating. Was the metallic precursor layer 57 completely implemented, as in the example of 5 the case remains, so remains on the back contact 52 a CIGS compound semiconductor layer 80 without residues of the metallic precursor layer.

Heating and holding 16 The coating at a temperature of at least 350 ° C during the duration of the process time is in the embodiments of the 1 and 3 advantageously realized in a continuous furnace, preferably in a segmented continuous furnace. 6 illustrates this by way of example with reference to a continuous furnace 90 which has two segments S1 and S2, in which the coating 63 can be brought to different temperatures. The illustrated continuous furnace 90 has an insertion opening 91 for introducing the substrates 50 and the layers arranged thereon in the continuous furnace 90 and a discharge opening 92 to run it from the continuous furnace 90 on. introduction opening 91 and discharge opening 92 are with a gas lock 96 provided to allow penetration of ambient air into the continuous furnace 90 to prevent. As gas locks 96 For example, gas curtains made of nitrogen or a noble gas can be used. In this way, compound semiconductor layers can be produced on an industrial scale in a continuous process.

To the substrates 50 and the layers arranged thereon in the continuous furnace 90 into it, through it and ultimately out of it again to transport, is a transport device 98 intended. This can in principle be any transport system known per se, for example a conveyor belt, roller transport devices or lifting beam systems.

The transport device 98 is preferably operated gradually. So can a glass substrate 50 with layers arranged thereon, first through the introduction opening 91 be introduced into the first segment S1 of the continuous furnace, where the coating is heated to a temperature of at least 350 ° C, so that a conversion of the metallic precursor layer in a compound semiconductor layer, in this case a CIGS compound semiconductor layer 80 , he follows. After the conversion, the glass substrate with the layers thereon is placed in the segment S2 of the continuous furnace 90 transported, in which by means of a cooling device 95 a cooling to a temperature of less than 300 ° C takes place. After this cooling, the glass substrates 50 and the layers thereon from the continuous furnace 90 transported out and the graphite plate 60 away.

For the purpose of heating the coating in the segment S1 is a heater 94 intended. In addition, inside the continuous furnace 90 a nitrogen atmosphere 93 designed to avoid unwanted reactions with oxygen or hydrogen described above.

6 shows an example of the use of the continuous furnace 90 in the process 1 , The continuous furnace 90 can obviously in an analogous manner in the embodiment of 3 Find use. In this case, the glass substrate would after the in 4 presented hang up 24 the one with the selenium coating 72 provided graphite plate 70 through the insertion opening 91 into the segment S1 of the continuous furnace 90 be introduced. After the conversion of the metallic precursor layer, there would be essentially the same layer sequence in the segment S2 as in FIG 6 is shown. Instead of the graphite plate 60 there would be only the graphite plate 70 on the prepared CIGS compound semiconductor layer 80 ,

In the presentation of the 6 lies the glass substrate 50 on the transport device 98 on. The glass substrate 50 is thus used as a carrier for the layers and graphite plates. Alternatively, it is possible to use the graphite plates used as a carrier. For this purpose, the glass substrates and layer sequences arranged thereon would only be upside down in the continuous furnace 90 introduce so that the graphite plates on the transport device 98 to come to rest. The glass substrates would then be on top. In this procedure, the graphite plates used are interpreted sufficiently stable.

8th illustrates another embodiment of the method according to the invention. This is one with a back contact 52 provided glass substrate 50 with a coating 63 provided, which has a metallic precursor layer and a chalcogen layer, wherein the chalcogen layer was deposited on the metallic precursor layer. The coating 63 For example, as related to the 1 and 2 be explained explained. Furthermore, the coating in the in 8th illustrated continuous furnace 99 heated and maintained at a temperature of at least 350 ° C for the duration of the process time. Here, the metallic precursor layer becomes the CIGS compound semiconductor layer 80 transformed.

In the embodiment of 8th becomes a continuous furnace 99 used, which largely in the 6 described continuous furnace 90 equivalent. In contrast to this is the continuous furnace 99 however, designed so that a majority of the free surface of the coating 63 with a wall 100 of the continuous furnace 99 can be brought into contact with each other. In this way, can be dispensed with a separate placement of a cover. Instead, the wall becomes 100 of the continuous furnace 99 used as a cover. To the surface contact between the coating 63 and the wall 100 can provide the transport device 98 be made adjustable, for example, in their vertical orientation. In this way, the coatings can 63 to the wall 100 moved up and so the area contact be provided.

The wall 100 of the continuous furnace 99 is advantageously made on its side facing the coating of a material with good thermal conductivity, preferably of graphite or silicon carbide.

The compound semiconductor layers produced by the process according to the invention, in particular CIGS compound semiconductor layers produced, can advantageously be used in the production of thin-film solar cells or thin-film solar cell modules. 7 shows such, known from the prior art solar cell 86 , Like a comparison of 7 with the representation in 5 shows, compound semiconductor layers prepared by the method according to the invention can be conveniently processed further to thin-film solar cells. Here, for example, a Cadmiumsulfidschicht 82 on the generated CIGS compound semiconductor layer 80 be applied. This is preferably done in a chemical bath. Finally, a zinc oxide layer 84 applied, for example by sputtering. A series connection of fabricated solar cells to a solar module can be realized with known, additional structuring steps.

LIST OF REFERENCE NUMBERS

10

Sputter metallic precursor layer on substrate

12

Depositing selenium layer

14

Provide surface contact

15a

predominant portion of the free surface of the coating

15b

free surface of the coating

16

Convert metallic precursor layer in compound semiconductor layer

18

Separate graphite plate from coating

24

Provide surface contact

25

free surface of the coating

50

glass substrate

52

back contact

54

Copper gallium layer

56

indium

57

metallic precursor layer

58

selenium layer

60

graphite plate

63

coating

70

graphite plate

72

selenium layer

80

CIGS compound semiconductor layer

82

Cadmium sulfide layer

84

zinc oxide

86

solar cell

90

Continuous furnace

91

introduction opening

92

discharge opening

93

nitrogen atmosphere

94

heater

95

cooling device

96

gas lock

98

transport device

99

Continuous furnace

100

wall

S1

First segment

S2

Second segment

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 patent literature

• EP 0662247 B1 [0004]
• WO 2009/033674 A2 [0005]
• WO 2009/135685 A2 [0005]

Claims (13)

Process for producing an I-III-VI compound semiconductor layer ( 80 ), in which - a substrate ( 50 ) with a coating ( 63 ) ( 10 . 12 ), which has a metallic precursor layer ( 57 ), - the coating ( 63 ) and maintained at temperatures of at least 350 ° C for the duration of a process time ( 16 ) and thereby the metallic precursor layer ( 57 ) in the presence of a chalcogen ( 58 ; 72 ) in the compound semiconductor layer ( 80 ) is converted ( 16 ), characterized in that between a predominant proportion ( 15a ) of a free surface ( 15a . 15b ; 25 ) of the coating ( 63 ) and a cover ( 60 ; 70 ) during the process time, at least at times a surface contact is provided ( 14 ; 24 ). Method according to claim 1, characterized in that before heating ( 16 ) of the coating ( 63 ) a chalcogen layer having at least one chalcogen ( 58 ) on the metallic precursor layer ( 57 ) is deposited ( 12 ) and the surface contact substantially between the chalcogen layer ( 58 ) and the cover ( 60 ) provided ( 14 ). Method according to one of the preceding claims, characterized in that a cover ( 70 ) is used ( 24 ), which at their the coating ( 63 ) facing side at least in sections with one or more chalcogens ( 72 ), preferably with selenium. Method according to one of the preceding claims, characterized in that the surface contact between the predominant portion ( 15a ) of the free surface ( 15a . 15b ; 25 ) of the coating ( 63 ) and the cover ( 60 ; 70 ) is provided during the entire process time ( 14 ; 24 ). Method according to one of the preceding claims, characterized in that the coating ( 63 ) together with the cover at least during the process time in a protective gas atmosphere ( 93 ), preferably in a nitrogen or inert gas atmosphere. Method according to one of the preceding claims, characterized in that during the conversion ( 16 ) of the metallic precursor layer ( 57 ) in the compound semiconductor layer ( 80 ) the chalcogens ( 58 ; 72 ) in amounts exceeding their respective stoichiometric proportion of the compound semiconductor layer formed ( 80 ) by 0% to 90%, preferably by 40% to 80%. Method according to one of the preceding claims, characterized in that as cover ( 60 ; 70 ) a plate ( 60 ; 70 ) is used ( 14 ; 24 ), preferably a silicon carbide plate and more preferably a graphite plate ( 60 ; 70 ) or a carbon fiber reinforced carbon plate. Method according to one of the preceding claims, characterized in that the surface contact between the predominant portion ( 15a ) of the free surface ( 15a . 15b ; 25 ) of the coating ( 63 ) and the cover ( 60 ; 70 ) is provided before the coating ( 63 ) for the purpose of warming and conversion ( 16 ) of the metallic precursor layer ( 57 ) into the compound semiconductor layer ( 80 ) in a furnace ( 90 ) is introduced. Method according to one of the preceding claims, characterized in that as cover a wall ( 100 ) of a furnace ( 99 ) is used, in which the coating ( 63 ) is heated ( 16 ). Method according to one of the preceding claims, characterized in that the metallic precursor layer ( 57 ) at a process pressure that is not more than 50 mbar lower than an atmospheric pressure in the compound semiconductor layer ( 80 ) is converted ( 16 ). Method according to one of the preceding claims, characterized in that the coating ( 63 ) in a continuous furnace ( 90 ) is heated ( 16 ). Method according to one of the preceding claims, characterized in that the metallic precursor layer ( 57 ) into a CIS or a CIGS compound semiconductor layer ( 80 ) is converted ( 16 ). Method according to one of the preceding claims, characterized in that the cover ( 60 ; 70 ) is heated before between it and the predominant portion of the free surface ( 15a . 14b ; 25 ) of the coating ( 63 ) the surface contact is formed ( 14 ; 24 ), preferably to a temperature of at least 400 ° C, and more preferably to a value of at least 600 ° C.

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