Structural And Chemical Analyses Of Sputtered In_xs_y Buffer Layers In Cu(in,ga)se_2 Thin-film Solar Cells

摘要

Sputtered In_xS_y layers deposited on borosilicate glass and Si at substrate temperatures ranging from about 60 ℃ to 340 ℃ were analyzed by means of X-ray diffraction, energy-dispersive X-ray spectrometry, and optical transmission and reflection measurements. With increasing substrate temperature, the In_xS_y layers exhibit increasing sulfur concentration and also increasing absorption-edge energies. In_xS_y, layers on Cu(In, Ga)Se_2(ClGS)/Mo/glass stacks were additionally studied by scanning and transmission electron microscopy. With increasing substrate temperature, Cu, Ga, and In interdiffusion between CIGS and In_xS_y becomes more enhanced. At 340 ℃, CuIn_5S_8 forms instead of In_xS_y The CuIn_5S_8 formation at elevated temperatures may be the reason for the very low efficiency of solar cells with indium sulfide buffers deposited at temperatures above about 250 ℃ by various techniques.