The preparation equipment and the preparation method of high transformation efficiency copper-indium-galliun-selenium film solar cell absorption layer
Technical field
The present invention relates to preparation equipment of a kind of copper-indium-galliun-selenium film solar cell absorption layer and preparation method thereof, belong to technical field of solar batteries.
Copper-indium-galliun-selenium (CIGS) thin-film solar cells is a kind of of multi-element compounds solar cell, and it has transformation efficiency height, good stability, good, the low cost and other advantages of anti-radiation performance.CIGS is copper-indium-galliun-selenium film solar cell absorption layer Chemical Composition CuIn
xGa
(1-x)Se
2Abbreviation.
Shown in accompanying drawing 1; Copper-indium-galliun-selenium film solar cell is the multi-layer film structure assembly, and its primary structure has: substrate (normally glass), back electrode (normally Mo), absorption layer (p-CIGS), impact plies (normally n-CdS), transparency conducting layer (normally intrinsic ZnO and Al doping ZnO bilayer structure), top electrode (being generally Ni/Al), antireflection layer (MgF normally
2, not necessarily to have).The structure of each tunic and characteristic all will influence the performance of CIGS battery.
The quality of absorption layer is directly restricting the performance of copper-indium-galliun-selenium film solar cell in the copper-indium-galliun-selenium film solar cell, thereby the preparation technology of absorption layer is very crucial in the preparation process of battery.If each elemental composition proportioning is improper in the film, then possibly form binary compounds such as CuxSey, InxSey, also possibly form like CuIn
5Se
8, CuIn
3Se
5, Cu
3In
5Se
9Wait other ternary compound, perhaps multiphase mixture, and undesired CuIn (Ga) Se
2Compound.And very confidential relation is also arranged between the ratio of component of the electricity of CIGS compound semiconductor, optical property and energy gap width and material, the stoichiometric ratio of various elements will directly influence the stability and the electricity conversion of copper-indium-galliun-selenium film solar cell in the CIGS rete.
At present, the preparation technology of copper-indium-galliun-selenium film solar cell absorption layer mainly contains two types of vacuum method and antivacuum methods, and wherein vacuum method mainly contains coevaporation method and preformed layer selenizing method; Adopting non-vacuum process mainly contains electrodip process, print process etc., and the present electricity conversion of CIS base battery of adopting non-vacuum process path of preparing is also lower,
The CIGS based thin film solar cell of in the world high-photoelectric transformation efficiency adopts coevaporation technology by American National renewable energy source laboratory (NREL) preparation up to now.Coevaporation can be divided into single stage method, two-step approach and three-step approach.Single stage method is when substrate temperature is 450-550 ℃, and whole elements of forming the CIGS absorption layer evaporate simultaneously.In film deposition process, adjust the vaporator rate of each element; With obtain to mix, stoichiometric ratio appropriate C IGS compound, whole one step of process accomplishes.This technology is because the processing parameter that relates to is adjusted more complicated, and whole process of preparation is difficult with control.
What the CIGS film of the high transformation efficiency of U.S. NREL adopted is three step coevaporation prepared.The first step, (400 ℃) evaporation In, Ga, Se form one deck In-Ga-Se initialization layer under the lower situation of base reservoir temperature, wherein control atomic ratio In: Ga=0.7: 0.3, (In+Ga): Se=2: 3; Second step, rising base reservoir temperature to 570 ℃, evaporation Cu, Se its objective is for by low-melting Cu
2-xThe characteristic that Se at high temperature has as the liquid phase promotes grain growing, obtains large size and fine and close rete, this two-layer compound CIGS that is converted into rich a little copper; The 3rd step kept the base reservoir temperature in second step, and evaporation In, Ga, Se make unnecessary Cu
2-xThe CIGS of stoichiometric ratios such as Se changes into continues a spot of In of evaporation, Ga, Se, can obtain the CIGS p type yellow copper structure of poor a little copper, and the ratio of control Cu/In+Ga is in this narrow and small scope of 0.88-0.92.Sample is cooled to 400 ℃ subsequently in evaporation Se, close Se cool to room temperature again.
Germany Wu Erte (wurth solar) also adopts coevaporation to carry out small-scale production.But the coevaporation difficult technique is realizing the good film forming of large-area uniformity, and repeatability also is difficult to control, therefore is not suitable for large-scale industrialized production.The advantage of coevaporation is can obtain to mix and stoichiometric ratio appropriate C IGS rete, and prerequisite is to want accurately to control the vaporator rate and the distribution of each evaporant, and this implements the comparison difficulty for big area.
Preformed layer selenizing method key step comprises: 1) prefabricated membrane preparation technology mainly prepares the blend films of Cu, In (Ga) alloy prefabricated membrane or Cu, In (Ga), Se through methods such as magnetron sputtering, method of evaporation.2) selenizing technology is mainly through (comprising selenium source and selenizing hydrogen source) under the atmosphere of selenium prefabricated membrane is annealed containing.Annealing temperature generally is controlled at 400~600 ℃.
At present preformed layer preparation technology that adopts of institute or employing accumulation formula structure are promptly done one deck copper film earlier, do one deck indium film (gallium film) again, perhaps do one deck selenium film again, and every tunic is thick all to have hundreds of nanometer even thousands of nanometer; Adopt the sputter of CuInGa mixing material target, but, be difficult to realize the accurate control of each elemental composition in the preformed layer and the mixing of atom magnitude because there is the selectivity sputter in mixing material.As the patent No. be ZL200510011858.9, Granted publication number for CN100413097C, Granted publication day be Augusts 20 in 2008 day, be called: the patent of " preparation method of copper-indium-galliun-selenium or copper indium gallium sulphur absorbing layer of thin film solar cell " discloses the preparation method of a kind of copper-indium-galliun-selenium or copper indium gallium sulphur solar battery obsorbing layer; Promptly adopt CuIn alloys target and CuGa alloys target; Or adopt the CuInGa alloys target as target, with the metal preformed layer of vacuum magnetic-control sputtering technology preparation CuInGa.Selenylation reaction or vulcanization reaction carry out in the another one Vakuumkammer; Earlier selenium source or sulphur source are evenly heated up; At metal preformed layer surface evaporation last layer selenium or sulphur; Through halogen tungsten lamp irradiation heating of metal preformed layer, selenizing or vulcanization reaction taking place, finally obtains copper-indium-galliun-selenium or copper indium gallium sulphur solar battery obsorbing layer again.
Number of patent application is 200910006531.0, publication number is CN101740660A, open day be June 16 in 2010 day, be called: the patented claim of " preparation method, the equipment of copper indium gallium selenium solar cell, its absorbing layer film and this film " discloses a kind of preparation method of copper indium gallium selenium solar cell absorbing layer film; The first step elder generation deposited copper, indium, gallium ternary metal film; Vapor deposition last layer selenium film forms the CIGS thin-film structure of nanometer scale again, repeats above-mentioned steps 10~50 times; Second step did short annealing with the CuInGaSe absorbed layer film that stacks up again and handles, and promptly obtained the polycrystalline copper-indium-galliun-selenium film of micron dimension.
Number of patent application is 201010118290.1; Publication number is CN101789469A, open day be July 28 in 2010 day, be called: the patented claim of " preparation method of light absorption layer of Cu-In-Ga-Se-S thin film solar cell " discloses a kind of preparation method of CIGSSe solar cell absorbing layer film; Promptly at first adopt magnetron sputtering method at substrate deposition Cu film; Adopt method of evaporation deposition In-Ga film then; Form (the layering of Cu-In-Ga alloy film; Also be alloy), once more with Cu-In-Ga alloy film and solid-state Se source or gaseous state H2Se source reaction generation copper-indium-galliun-selenium (CIGS) film, at last with CIGS film and solid-state S simple substance or gaseous state H2S source reaction generation Cu-In-Ga-Se-S (CIGSS) light-absorption layer film.
Though preformed layer selenizing method is considered to the most effectual way of present large-area preparation copper-indium-galliun-selenium film solar cell; But because the CuInGa film that this method is prepared is an accumulation formula structure; The inner chemical ingredients of rete is uneven at film thickness direction; This ununiformity though the diffusion during selenizing has weakened; But its existence still can make the efficiency of conversion (laboratory 14% ±) of the battery that this method makes be lower than the efficiency of conversion (20% ±) of coevaporation method laboratory sample, and efficiency of conversion is just lower in the industrial production.
Summary of the invention
The present invention provides a kind of preparation equipment scheme and corresponding preparation method of new copper-indium-galliun-selenium film solar cell absorption layer, is difficult to accurately control and large-area uniformity defect of bad and preformed layer selenizing method rete inside chemical ingredients in the uneven defective of film thickness direction to overcome above-mentioned coevaporation.Use this scheme and method can more be leveled off to the absorbing layer film of each element chemistry of theoretical CIGS absorption layer metering ratio; And be easy to control; Repeatability improves greatly, therefore obtains copper-indium-galliun-selenium (CIGS) thin-film solar cells of high-photoelectric transformation efficiency.The raising of cell photoelectric efficiency of conversion can make the manufacturing cost of battery unit's generated energy and power plant's running cost all be reduced, and can advance sun power to substitute the process of fossil energy, promotes the well-being of mankind.
The Vakuumkammer of present device is divided into two vacuum areas, and wherein a side is a sputtering zone, and opposite side is an evaporating area.Said sputtering target material also can be the alloy material or the spliceosome of two or three element for required Cu, In, the Ga element single component material of preparation CIGS absorption layer, and the quantity of sputtering target and target kind all is no less than two kinds.Said evaporation source is required Se source or the S source of preparation CIGS absorption layer.This subregion film forming can be avoided the pollution to the metal or alloy target of Se or S atmosphere, influences controllability, the repeatability of metal or alloy target as sputter.
One of characteristics of the present invention are that workpiece to be plated (plated film substrate) becomes the cylindric setting of arranging; Sputtering target material and Se or S evaporation source are distributed in workpiece by surfacing one side; Relative high speed rotating between workpiece and the target (comprising Se or S evaporation source); In the process of accomplishing the necessary thicknesses of layers of whole absorption layer, rotating cycle is greater than 500.This high speed rotating can make each even film layer of gained CIGS mix, and is similar to coevaporation technology, and unlike the stacked structure of traditional technology." ideal " speed of rotation is the speed with a molecular layers thick rete of growth on the workpiece that whenever rotates a circle in theory; And the speed of rotation of actual " enough high " refers to the speed of the slowest feasible economy; Under this speed, the uneven components property that institute's film forming layer causes at film thickness direction draws the result that the cell photoelectric efficiency of conversion obtains than the Reasonable Speed film forming after selenizing do not have obvious decline.
Relation between said workpiece and the target (comprising the Se evaporation source) has two kinds of designs: see accompanying drawing 2 for first kind; Workpiece is in interior target (comprising the Se evaporation source) mode outside; Target (comprising Se or S evaporation source) is static with respect to the coating equipment Vakuumkammer during this mode plated film; Work rest is inboard with respect to the rotation of coating equipment Vakuumkammer at target (comprising Se or S evaporation source), and this mode is applicable to the preparation of uniset glass or flexible substrates absorption layer; See accompanying drawing 3 for second kind; Workpiece is the mode of target (comprising Se or S evaporation source) outside; Workpiece is static with respect to the coating equipment Vakuumkammer during this mode plated film; With respect to the rotation of coating equipment Vakuumkammer, this mode is applicable to the preparation of intermittent continuous flexible substrates absorption layer to target (comprising Se or S evaporation source) in the workpiece inboard.
Two of characteristics of the present invention are accurate film thickness monitoring systems.In the spatter film forming system; Power becomes reasonable linear relationship with sedimentation rate; Even the linear relationship that is not strict; The repeatability of its process and the stability of time are also very good, and the desirable stoichiometric ratio of therefore in absorption layer, controlling Cu, In, Ga element by method provided by the invention can conveniently realize.The control of desirable absorption layer Se element is the key of system of the present invention.We have used thickness and sedimentation rate TT&C system on the work rest that we develop voluntarily in the control of Se element, and this system's probe places on the work rest, in coating process, can measure thicknesses of layers and rate of film build in real time.Because Cu, In, Ga element use spatter film forming; Be easy to control; The task of this rate of film build TT&C system mainly is the evaporation control that is used for the Se element; Make its sedimentation rate be matched with the sedimentation rate of Cu, In, Ga element, and then obtain all ideal absorbing layer film of stoichiometric ratio and homogeneity.
Use present device can realize following four kinds of CIGS absorption layer preparation technologies: first kind; Earlier obtain all ideal CuInGa preformed layers of stoichiometric ratio and homogeneity with sputtering method; Take out from coating chamber, send into and under the atmosphere of Se, carry out the selenizing processing in the special-purpose vacuum selenizing stove; Second kind; Earlier obtain all ideal CuInGa retes of stoichiometric ratio and homogeneity with sputtering method; At method deposition one deck Se of CuInGa rete external application evaporation layer, perhaps CuInGa is divided into the several stages film forming again, carries out the film forming of Se element after the CuInGa film forming in each stage; All again workpiece is being taken out from coating chamber after the preformed layer completion, sending into and carry out the selenizing processing in the heat treatment furnace; The third is heated to proper temperature with workpiece before plated film, carries out the sputter coating of CuInGa element and the evaporation coating of Se element simultaneously, treat that rete has plated after, be warmed up to the selenizing temperature again, make rete generation selenylation reaction, make absorption layer; The 4th kind, workpiece is heated to proper temperature before the plated film, carry out the sputter coating of CuInGa element and the evaporation coating of Se element simultaneously, treat that rete has plated after, workpiece is taken out from coating chamber, send into and carry out the selenizing processing in the heat treatment furnace.
Description of drawings
Fig. 1 is the structural representation of CIGS thin-film solar cells;
Scheme one structural representation of the preparation equipment of the copper-indium-galliun-selenium film solar cell absorption layer that Fig. 2 provides for embodiment of the present invention (workpiece at interior target outside);
Scheme two structural representations of the preparation equipment of the copper-indium-galliun-selenium film solar cell absorption layer that Fig. 3 provides for embodiment of the present invention (workpiece target interior) outside;
Fig. 4 is the schematic top plan view of the scheme one actual coating equipment of preparation equipment;
Fig. 5 is a selenium take-up stand synoptic diagram.
Embodiment
This embodiment provides preparation equipment of a kind of copper-indium-galliun-selenium film solar cell absorption layer and preparation method thereof; Like Fig. 2~shown in Figure 5; The preparation equipment of copper-indium-galliun-selenium film solar cell absorption layer comprises coating equipment; Said coating equipment comprises Vakuumkammer 1, work rest 2, sputtering target 3 and selenium vaporizer 4; Sputtering target 3 and selenium vaporizer 4 corresponding being arranged in the Vakuumkammer 1, work rest 2 is arranged in the Vakuumkammer 1 and towards the evaporating area 11 of the sputtering zone 12 and the selenium vaporizer 4 of sputtering target 3 for cylindric.The material of said sputtering target 3 also can be the alloy material or the spliceosome of two or three element for required Cu, In, the Ga element single component material of preparation CIGS absorption layer, and the quantity of sputtering target and target kind all is no less than two kinds.Said evaporation source is required Se source or the S source of preparation CIGS absorption layer.This subregion film forming can be avoided the pollution to the metal or alloy target of Se or S atmosphere, influences controllability, the repeatability of metal or alloy target as sputter.
As shown in Figure 2, be labeled as 1 be Vakuumkammer, work rest 2 is concentric with Vakuumkammer 1, sputtering target 3 is fixed on the inwall of Vakuumkammer 1 with selenium vaporizer 4, sputtering target 3 and selenium vaporizer 4 transfixions, work rest 2 rotates.
As shown in Figure 3; Be labeled as 1 be Vakuumkammer, sputtering target 3 is fixed on the outer wall of a cylinder-shaped bracket 14 with selenium vaporizer 4, sputtering target 3 rotates with cylinder-shaped bracket 14 with selenium vaporizer 4; Mark 7 is turning directions of cylinder-shaped bracket 14; Work rest 2 is arranged on the outside of sputtering target 3 and selenium vaporizer 4, be labeled as 6 be flexible workpiece, mark 8 is flexible workpiece intermittent delivery directions.
As shown in Figure 4; Be labeled as 1 be Vakuumkammer, work rest 2 is concentric with Vakuumkammer 1, sputtering target 3 is fixed on the inwall of Vakuumkammer 1 with selenium vaporizer 4; Sputtering target 3 and selenium vaporizer 4 transfixions; Coating equipment comprises two molecular pumps 9, and said two molecular pumps 9 are connected with evaporating area 11 with Vakuumkammer 1 interior sputtering zone 12 respectively, and mark 10 is work rest turning directions.
As shown in Figure 5; Selenium vaporizer 4 also comprises metal tube 6 and two electrodes 13; Said metal tube 6 is connected with the outlet of selenium vaporizer 4, and shut two ends of metal tube 6, has aperture 10 on the tube wall of metal tube 6; The sectional area sum of all apertures 10 is less than the sectional area of selenium vaporizer 4 outlets, and the two ends of metal tube 6 are connected to electrode 13.
As shown in Figure 4, coating equipment is a Vakuumkammer diameter 1680mm, the vertical box coating equipment of Vakuumkammer height 1250mm.The outside that the sputtering target of coating equipment configuration and selenium evaporation source (selenium vaporizer) are distributed in the rotational workpieces frame, work rest diameter 1380mm, sputter homogeneity range scope is height 680mm, the work rest rotating speed can reach 100 rev/mins.
In an embodiment, use be Cu single component target, CuGa alloy target material, three kinds of sputtering target materials of In single component target, target is the long direct current planar target of 998mm, target material surface is apart from workpiece surface 60mm.
It is cylindric that work rest totally is, and cylindrical outer surface can clamping inflexible glass and flexible stainless steel plate, and the far-infrared heating device is set inside and outside the cylinder, and heating unit can make the workpiece to be plated temperature be elevated to 600 degrees centigrade.
Sputtering zone and Se evaporating area are carried out vacuum insulation and (promptly between sputtering zone and Se evaporating area, relative high vacuum region are set; Reduce interactional degree between sputtering zone and the Se evaporating area); Two isolated areas are set, and it is that 3500 liters/second turbomolecular pump is bled that corresponding each isolated area has two pumping speed.
As shown in Figure 5, the Se evaporating area is provided with a Se vaporizer, and the direct subtend work rest of outlet of vaporizer Se gets final product when making the small area sample; When needing to make the big area sample, need install the take-up stand of a Se additional in the outlet of vaporizer Se.This take-up stand main body is one section metal tube, and metal tube links to each other with the outlet of vaporizer Se, and shut the metal tube end; Tube wall has aperture, and all aperture sectional area sums are less than the sectional area of the outlet of vaporizer Se, are connected to electrode at the two ends of metal tube; In the process of evaporation selenium, switch on to metal tube; Because the existence of metal tube resistance, metal tube can be heated, and suitably regulates electric current Se steam can not condensed in the inboard of metal tube and overflow from aperture.
Thicknesser probe on the work rest in height faces the outlet of vaporizer Se.
Can realize following four kinds of preparing methods by the preparation equipment of above-mentioned copper-indium-galliun-selenium film solar cell absorption layer:
First method: the glass that 1. will plate the Mo electrode layer coating equipment Vakuumkammer (being fixed on the work rest) of packing into, 2. close door for vacuum chamber and vacuumize, open workpiece and rotate (2 rev/mins), 3. the Vakuumkammer background pressure reaches 5*10
-3Pa imports Ar gas (flow 800SCCM) at sputtering zone, prepares beginning plated film (before the plated film workpiece rotational frequency being brought up to 100 rev/mins); 4. open sputtering target by the power parameter of design in advance, observe sedimentation rate and it is controlled in the technological design value scope, treat that 5. the CuInGa thicknesses of layers reaches 600nm; Close sputtering target, 6. Vakuumkammer inflation is taken out workpiece from coating chamber; 7. workpiece is sent into and carried out the selenizing processing in the heat treatment furnace, make rete generation selenylation reaction, make absorption layer.
Second method: the glass that 1. will plate the Mo electrode layer coating equipment Vakuumkammer (being fixed on the work rest) of packing into; 2. closing door for vacuum chamber vacuumizes and heats; Open workpiece and rotate (2 rev/mins), 3. workpiece temperature reaches 250 degrees centigrade, and the Vakuumkammer background pressure reaches 5*10
-3Pa imports Ar gas (flow 800SCCM) at sputtering zone, prepares beginning plated film (before the plated film workpiece rotational frequency being brought up to 100 rev/mins), 4. opens sputtering target by the power parameter of design in advance; Observe sedimentation rate and it is controlled in the technological design value scope, when treating that 5. the CuInGa thicknesses of layers reaches 200nm, close sputtering target, preheating Se vaporizer; Strengthen the heating power of Se vaporizer then, the Se layer of deposition ± 340nm is closed the Se vaporizer; 6. repeat again 4., 5. step twice, 7. Vakuumkammer inflation is taken out workpiece from coating chamber; 8. workpiece is sent into and carried out the selenizing processing in the heat treatment furnace, make rete generation selenylation reaction, make absorption layer.
The third method: the glass that 1. will plate the Mo electrode layer coating equipment Vakuumkammer (being fixed on the work rest) of packing into; 2. closing door for vacuum chamber vacuumizes and heats; Open workpiece and rotate (2 rev/mins), 3. workpiece temperature reaches 550 degrees centigrade, and the Vakuumkammer background pressure reaches 5*10
-3Pa imports Ar gas (flow 800SCCM), preheating Se vaporizer at sputtering zone; Prepare the beginning plated film, 4. before the plated film workpiece rotational frequency is brought up to 100 rev/mins, open sputtering target by the power parameter of design in advance; And strengthen the heating power of Se vaporizer, observe sedimentation rate and it is controlled at (sedimentation rate of CuInGa component is known in advance, under the identical sputtering power parameter of design in advance, can reproduce this sedimentation rate well in the technological design value scope; Add the sedimentation rate of the Se of prior design, be exactly total the sedimentation rate of four kinds of components of CuInGaSe that will obtain now), treat that 5. thickness reaches 1600nm; Close sputtering target, deposit the Se layer of 100nm again, close the Se vaporizer; 6. reduce rotating speed to 2 rev/min, close heating, make workpiece cool to 250 degrees centigrade; 7. Vakuumkammer inflation is taken out workpiece from coating chamber, make absorption layer.
The 4th kind of method: the glass that 1. will plate the Mo electrode layer coating equipment Vakuumkammer (being fixed on the work rest) of packing into; 2. closing door for vacuum chamber vacuumizes and heats; Open workpiece and rotate (2 rev/mins), 3. workpiece temperature reaches 250 degrees centigrade, and the Vakuumkammer background pressure reaches 5*10
-3Pa imports Ar gas (flow 800SCCM), preheating Se vaporizer at sputtering zone; Prepare the beginning plated film, 4. before the plated film workpiece rotational frequency is brought up to 100 rev/mins, open sputtering target by the power parameter of design in advance; And strengthen the heating power of Se vaporizer, observe sedimentation rate and it is controlled at (sedimentation rate of CuInGa component is known in advance, under the identical sputtering power parameter of design in advance, can reproduce this sedimentation rate well in the technological design value scope; Add the sedimentation rate of the Se of prior design, be exactly total the sedimentation rate of four kinds of components of CuInGaSe that will obtain now), treat that 5. thickness reaches 1600nm; Close sputtering target, the Se layer of deposition ± 100nm is closed the Se vaporizer again; 6. Vakuumkammer inflation is taken out workpiece from coating chamber, 7. workpiece is sent into and carried out the selenizing processing in the heat treatment furnace; Make rete generation selenylation reaction, make absorption layer.
The above; Be merely the preferable embodiment of the present invention, but protection scope of the present invention is not limited thereto, any technician who is familiar with the present technique field is in the technical scope that the present invention discloses; The variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claims.