Formation of cigs absorber layer materials using atomic layer deposition and high throughput surface treatment on coiled flexible substrates

Abstract

An absorber layer may be formed on a substrate using atomic layer deposition reactions. An absorber layer containing elements of groups IB, IIIA and VIB may be formed by placing a substrate in a treatment chamber and performing atomic layer deposition of a group IB element and/or one or more group IIIA elements from separate sources onto a substrate to form a film. A group VIA element is then incorporated into the film and annealed to form the absorber layer. The absorber layer may be greater than about 25 nm thick. The substrate may be coiled into one or more coils in such a way that adjacent turns of the coils do not touch one another. The coiled substrate may be placed in a treatment chamber where substantially an entire surface of the one or more coiled substrates may be treated by an atomic layer deposition process. One or more group IB elements and/or one or more group IIIA elements may be deposited onto the substrate in a stoichiometrically controlled ratio by atomic layer deposition using one or more self limiting reactions.

1 . A method for forming an absorber layer containing elements of groups IB, IIIA and VIA, comprising the steps of:
 atomic monolayer resolution tuning of a bandgap grading of a precursor layer on a substrate, wherein the tuning occurs with spatial uniformity and resolution through deposition of partial atomic monolayers with aggregate growth rate directly proportional to a number of reaction cycles rather than the pressure or concentration of precursor gases in the chamber, with control over film thickness, film uniformity, and conformality;   wherein after exposure to a precursor agent and then a reducing agent, atoms from each of the partial atomic monolayers occupy only a portion of all deposition sites on a target surface;   repeating atomic monolayer deposition until a desired atomically-graded deposition profile is formed in the precursor layer.   
     
     
         2 . The method of  claim 1  wherein the absorber layer is between about 25 nm and about 5000 nm thick. 
     
     
         3 . The method of  claim 1  wherein the absorber layer is between about 25 nm and about 3000 nm thick. 
     
     
         4 . The method of  claim 1  wherein the absorber layer is between about 100 nm and about 2000 nm thick. 
     
     
         5 . The method of  claim 1  wherein the absorber layer is between about 500 nm and about 2000 nm thick. 
     
     
         6 . The method of  claim 1  wherein the absorber layer is between about 1000 nm and about 2000 nm thick. 
     
     
         7 . The method of  claim 1  wherein the substrate is coiled in the treatment chamber. 
     
     
         8 . The method of  claim 7  wherein the precursor layer is formed by atomic layer deposition carried out in a stoichiometrically controlled ratio using one or more self-limiting reactions involving precursor gases of the group IB and group IIIA elements in a mix ratio that translates into a deposition ratio of the group IB and IIIA elements on the substrate, and/or by an atomic layer deposition sequence involving two or more self-limiting single species deposition reactions with precursor gases of the group IB and group IIIA elements; and
 incorporating an element of group VIA into the absorber layer. 
 
     
     
         9 . The method of  claim 7  wherein the element of group VIA is selenium or sulfur. 
     
     
         10 . The method of  claim 7  wherein incorporating the element of group VIA into the absorber layer includes exposing the film to selenium vapor, sulfur vapor, H 2 Se, H 2 S, one or more other selenium- or sulfur-containing compounds, or combinations or mixtures of two or more of these. 
     
     
         11 . The method of  claim 7  wherein incorporating the element of group VIA into the absorber layer involves using one or more precursor gases containing one or more elements of group VIA. 
     
     
         12 . The method of  claim 11  wherein the element of group VIA is incorporated into the absorber film through a sequence of atomic layer deposition steps. 
     
     
         13 . The method of  claim 11  wherein the sequence of atomic layer deposition steps includes the use of one or more metal organic precursors containing selenium, sulfur, H 2 Se, H 2 S, one or more other selenium- or sulfur-containing compounds, or combinations or mixtures of two or more of these. 
     
     
         14 . The method of  claim 13  wherein the one or more metal organic precursors containing selenium or sulfur include dimethyl selenide, dimethyl diselenide, or diethyl diselenide. 
     
     
         15 . The method of  claim 14  wherein incorporating the element of group VIA takes place either on a monolayer by monolayer basis, or periodically, with an exposure period substantially longer than a monolayer deposition cycle, or at the end of an absorber layer deposition sequence. 
     
     
         16 . The method of  claim 1  wherein performing atomic layer deposition includes exposing the substrate to one or more precursors of copper, indium, and/or gallium, and/or aluminum, and/or selenium, and/or sulfur. 
     
     
         17 . The method of  claim 16  wherein the precursors include one or more Cu(I) compounds, one or more Cu(II) compounds, CuCl, copper iodide, or other copper halides, one or more copper diketonates, Cu(II)-2,2,6,6,-tetramethyl-3,5,-heptanedionate (Cu(thd) 2 )), Cu (II) 2,4-pentanedionate, Cu(II) hexafluoroacetylacetonate (Cu(hfac) 2 ), Cu(II) acetylacetonate (Cu(acac) 2 ), Cu(II) dimethylaminoethoxide, one or more copper ketoesters, one or more organocopper precursors containing Si or Ge, one or more other organocopper precursors and combinations or mixtures of the above, indium chloride, indium iodide, one or more other indium halides, dimethylindium chloride, trimethylindium, indium 2,4-pentanedionate (indium acetylacetonate), indium hexafluoropentanedionate, indium methoxyethoxide, indium methly(trimethylacetyl)acetate, indium trifluoropentanedionate, one or more organoindium precursors containing Si or Ge, one or more other organoindium precursors, and combinations or mixtures of the above, diethylgallium chloride, gallium triiodide, one or more other gallium halides, Ga (III) 2,4-pentanedionate, Ga (III) ethoxide, Ga(III) 2,2,6,6,-tetramethylheptanedionate, tris(dimethylaminogallium), gallium (I) salts, gallium chloride, gallium fluoride, gallium iodide, gallium acetate, other gallium (I)-based organometallic precursors, one or more organogallium precursors containing Si or Ge, one or more other organogallium precursors and combinations or mixtures of the above, aluminum chloride, aluminum iodide, or other halides, dimethylaluminum chloride, one or more aluminum butoxides, aluminum di-s-butoxide ethylacetoacetate, aluminum diisopropoxide ethylacetoacetate, aluminum ethoxide, aluminum isopropoxide, aluminum hexafluoropentanedionate, Al(III) 2,4,-pentanedionate, AI(III) 2,2,6,6-tetramethyl-3,5-heptanedionat-e, aluminum trifluoroacetate, trisisobutylaluminum, aluminum silicate, one or more organoaluminum or organometallic precursors containing Si or Ge, one or more other organoaluminum or other organometallic precursors and combinations or mixtures of the above. 
     
     
         18 . The method of  claim 16  further comprising, after exposing the substrate to one or more organometallic precursors of copper, indium, and/or gallium, and/or aluminum, and/or selenium, and/or sulfur, exposing the substrate to one or more reducing agents or proton-donor compounds. 
     
     
         19 . The method of  claim 18  wherein the one or more reducing agents or proton donor compounds include water (H 2 O), hydrogen peroxide (H 2 O 2 ), methanol, ethanol, isopropyl alcohol, one or more butyl alcohols, one or more other alcohols, carbon monoxide (CO), Oxygen gas (O 2 ), formalin, or combinations or mixtures of two or more of these. 
     
     
         20 . The method of  claim 1  wherein the precursor layer is formed by performing atomic layer deposition of one or more group IB elements and one or more group IIIA elements and includes an atomic layer deposition sequence involving two or more self-limiting single species deposition reactions with precursor gases of the group IB and group IIIA elements and varying the sequence of exposure pulses of the precursor gases.