The Optical Property Characterization of AgGaTe₂ Prepared by the Two-Step Closed Space Sublimation

Abstract

Since its bandgap is close to optimum value, AgGaTe 2 is regarded as a promising material for solar cells. This paper reports the result of photoluminescence (PL) experiments on AgGaTe 2 thin films prepared by the twostep closed space sublimation method. In particular, the effect of by-products including Ag 2 Te or AgGa 5 Te 8 on PL properties of AgGaTe 2 is investigated. The radiative recombination process is also explored. PL measurements of thin films are performed by changing the excitation intensity and measured temperature. It is confirmed that the emission band probably derived from defects and impurities exists near 1.02 eV and the emission band derived from free exciton (FE) exists around 1.32 eV, and the variation of FE emission intensity is affected by the Ag/Ga ratio in AgGaTe 2 . It is also investigated that the activation energy (E A ) of the FE emission is about 7.8 meV.