Effects of annealing atmosphere on the performance of Cu(InGa)Se₂films sputtered from quaternary targets

Abstract

Quaternary sputtering without additional selenization is a low-cost alternative method for the preparation of Cu(InGa)Se 2 (CIGS) thin film for photovoltaics. However, without selenization, the device efficiency is much lower than that with selenization. To comprehensively examine this problem, we compared the morphologies, depth profiles, compositions, electrical properties and recombination mechanism of the absorbers fabricated with and without additional selenization. The results revealed that the amount of surface Se on CIGS films annealed in a Se-free atmosphere is less than that on CIGS films annealed in a Se-containing atmosphere. Additionally, the lower amount of surface Se reduced the carrier concentration, enhanced the resistivity of the CIGS film and allowed CIGS/CdS interface recombination to be the dominant recombination mechanism of CIGS device. The increase of interface recombination reduced the efficiency of the device annealed in a Se-free atmosphere.

Influence of The Substrate-Target Angle and Sputter Temperature On The Properties of CIGS Thin Films Sputtered From Single Quaternary Target

“…A more practical and effective way of deposition of CIGS absorber layer is the single-step sputtering by using a quaternary target [10][11][12][13][14]. Sputtering directly from a single target provides good uniformity of thin film and simplification of process by eliminating the postselenization-which paves the way for mass production along with the reduced material cost [15][16][17][18].…”