Thin-film devices formed from solid group iiia particles

Abstract

Methods and devices are provided for forming thin-films from solid group IIIA-based particles. In one embodiment of the present invention, a method is described comprising of providing a first material comprising an alloy of a) a group IIIA-based material and b) at least one other material. The material may be included in an amount sufficient so that no liquid phase of the alloy is present within the first material in a temperature range between room temperature and a deposition or pre-deposition temperature higher than room temperature, wherein the group IIIA-based material is otherwise liquid in that temperature range. The other material may be a group IA material. A precursor material may be formulated comprising a) particles of the first material and b) particles containing at least one element from the group consisting of: group IB, IIIA, VIA element, alloys containing any of the foregoing elements, or combinations thereof. The temperature range described above may be between about 20° C. and about 200° C. It should be understood that the alloy may have a higher melting temperature than a melting temperature of the IIIA-based material in elemental form.

1 . A multilayer structure to form a Group IBIIIAVIA compound absorber for solar cells, comprising: a base comprising a substrate; a first layer formed on the base, the first layer comprising an indium-gallium-selenide film wherein the gallium to (gallium plus indium) molar ratio of the indium-gallium-selenide film is in the range of 0 to 0.8; and a metallic layer formed on the first layer, the metallic layer comprising gallium and indium without a Group VIA material, wherein the first layer and the metallic layer are distinct layers with no substantial reaction therebetween. 
     
     
         2 . The multilayer structure of  claim 1  wherein indium and gallium in the metallic layer form a stack comprising at least one indium film and at least one gallium film. 
     
     
         3 . The multilayer structure of  claim 1 , wherein the first layer further comprises a copper film, and wherein the indium-gallium-selenide film and the copper film are distinct films with no substantial reaction therebetween. 
     
     
         4 . The multilayer structure of  claim 3  wherein the copper film is interposed between the base and the indium-gallium-selenide film. 
     
     
         5 . The multilayer structure of  claim 3  wherein the metallic layer further comprises copper. 
     
     
         6 . The multilayer structure of  claim 5  wherein a ratio of number of moles of gallium to the total number of moles of gallium and indium in the metal layer is in the range of 0.2-0.3.9. 
     
     
         7 . The multilayer structure of  claim 3  wherein a ratio of number of moles of gallium to the total number of moles of gallium and indium in the metal layer is in the range of 0.2-0.3.8. 
     
     
         8 . The multilayer structure of  claim 3  wherein the copper film is interposed between the indium-gallium-selenide film and the metallic layer. 
     
     
         9 . The multilayer structure of  claim 8  wherein a ratio of number of moles of gallium to the total number of moles of gallium and indium in the metal layer is in the range of 0.2-0.3. 
     
     
         10 . The multilayer structure of  claim 2  wherein the metallic layer further comprises metallic stack including at least one copper film, wherein the gallium and indium without the Group VIA material form one metal layer different than the at least one copper film. 
     
     
         11 . The multilayer structure of  claim 10  wherein a ratio of number of moles of gallium to the total number of moles of gallium and indium in the metal layer is in the range of 0.2-0.3. 
     
     
         12 . The multilayer structure of  claim 1  wherein the metallic layer further comprises copper. 
     
     
         13 . The multilayer structure of  claim 1  wherein a ratio of number of moles of gallium to the total number of moles of gallium and indium in the metal layer is in the range of 0.2-0.3. 
     
     
         14 . A process of forming a Group IBIIIAVIA absorber on a base, comprising:
 forming a first layer comprising an indium-gallium-selenide compound film on the base; forming a metallic layer on the first layer, the metallic layer comprising a Group IB metal, a Group IIIA metal and another Group IIIA metal without a Group VIA material, wherein the base is at a substantially ambient temperature when the metallic layer is formed, and wherein the first layer and the metallic layer are distinct layers with no substantial reaction therebetween; and reacting the first layer, the metallic layer and a Group VIA material.   
     
     
         15 . The process of  claim 14 , wherein the first layer further comprises a first metal film of a Group IB metal, wherein the indium-gallium-selenide compound material film is deposited over the first metal film at a substantially ambient temperature. 
     
     
         16 . The process of  claim 14 , wherein forming the metallic layer comprises:
 depositing a copper film onto the first layer; depositing a gallium film onto the copper film; and   depositing an indium film onto the gallium film.   
     
     
         17 . The process of  claim 16 , wherein forming the metallic layer further comprises depositing another copper film onto the indium film. 
     
     
         18 . The process of  claim 14 , wherein the gallium to indium molar ratio of the indium-gallium-selenide compound film is in the range of 0 to 0.8. 
     
     
         19 . The process of  claim 14 , wherein a molar ratio of gallium to indium in the metallic layer is in the range of 0.2 to 0.3. 
     
     
         20 . The process of  claim 14 , wherein the step of reacting comprises depositing a Group VIA material on the metallic layer, thereby forming a pre-absorber structure, and heating the pre-absorber structure 200-600° C.