비진공법 CuInSe 2 태양전지에서 MoSe 2 의 생성을 억제하기 위한 산화몰리브데늄 확산장벽 층

Two-step processes for preparing Cu(In,Ga)Se 2 absorber layers consist of precursor layer formation and subsequent annealing in a Se-containing atmosphere. Among the various deposition methods for precursor layer, the nonvacuum (wet) processes have been spotlighted as alternatives to vacuum-based methods due to their potential to realize low-cost, scalable PV devices. However, due to its porous nature, the precursor layer deposited on Mo substrate by nonvacuum methods often suffers from thick MoSe 2 formation during selenization under a high Se vapor pressure. On the contrary, selenization under a low Se pressure to avoid MoSe 2 formation typically leads to low crystal quality of absorber films. Although TiN has been reported as a diffusion barrier against Se1), the additional sputtering to deposit TiN layer may induce the complexity of fabrication process and nullify the advantages of nonvacuum deposition of absorber film. In this work, Mo oxide layers via thermal oxidation of Mo substrate have been explored as an alternative diffusion barrier. The morphology and phase evolution was examined as a function of oxidation temperature. The resulting Mo/Mo oxides double layers were employed as a back contact electrode for CuInSe 2 solar cells and were found to effectively suppress the formation of MoSe 2 layer.