Sputter deposited sub-stochiometric MoOx thin film as hole-selective contact layer for silicon based heterojunction devices

Abstract We investigated the electronic properties of sputtered sub-stoichiometric molybdenum oxide (MoOx) thin films on crystalline silicon (c-Si) wafer. Structural analysis of the MoOx films growth indicated that the deposition temperature plays a crucial role. The MoOx film growth at ~250 °C showed relatively large work function in comparison to growth at ~22 °C by the Kelvin probe force microscopy analysis. The large work function of the MoOx film led to an inversion layer formation at the c-Si/MoOx interface with the sufficient electronic band banding in the c-Si, which verified by conducting atomic force microscopy analysis. Recombination channels at the c-Si/MoOx interface suppressed by a chemically-grown SiOx buffer layer on the c-Si surface prior to the MoOx film deposition, which enhanced the minority carrier lifetime of c-Si from ~12 μs to ~32 μs. The non-ideal diode behavior observed from the c-Si/MoOx structure due to the trap-assisted carrier recombination at the interface in forward voltage bias condition. Impedance analysis also carrier out to understand the charge carrier recombination and resistance during transport at the c-Si/MoOx interface with and without SiOx buffer layer. The carrier-selective contact c-Si/MoOx cell power conversion efficiency enhanced from ~3.0% to ~4.3% after the SiOx passivation layer inclusion between the c-Si and MoOx.