Abstract: Provided are light emitting diodes (LEDs) and methods of fabricating such LEDs. Specifically, an LED has an epitaxial stack and current distribution layer disposed on and interfacing the epitaxial stack. The current distribution layer includes indium oxide and zinc oxide such that the concentration of indium oxide is between about 5% and 15% by weight. During fabrication, the current distribution layer is annealed at a temperature of less than about 500° C. or even at less than about 400° C. These low anneal temperature helps preserving the overall thermal budget of the LED while still yielding a current distribution layer having a low resistivity and low adsorption. A particular composition and method of forming the current distribution layer allows using lower annealing temperatures. In some embodiments, the current distribution layer is sputtered using indium oxide and zinc oxide targets at a pressure of less than 5 mTorr.

Abstract: Methods of forming CZTS absorber layers in a TFPV device with a graded bandgap with or without a graded concentration are provided. In general, a Cu—Zn—Sn—(S, Se) precursor film is formed by sputtering. The Cu—Zn—Sn—(S, Se) precursor film can be formed as a single layer or as a multilayer stack. The composition may be uniform or graded throughout the thickness of the film. In some embodiments, the sputtering is performed in a reactive atmosphere including a chalcogen source (e.g. H2S, H2Se, etc.). The films, in conjunction with a subsequent selenization or anneal process, are converted to an absorber layer.