Effect of Silicon Surface Treatment on the Electrical and Photoelectric Properties of Nanostructured MoOx/n-Si Heterojunctions

Abstract

The paper presents the results of studies of the effect of silicon surface treatment on the electrical and photoelectric properties of nanostructured MoO_x/n-Si heterojunctions. The nanostructured heterojunctions MoO_x/n-Si, were prepared by deposition of thin films of molybdenum oxide (n-type conductivity) by reactive magnetron sputtering in the universal vacuum system Leybold Heraeus L560 on the nanostructured silicon substrates (n-type conductivity), which were made by chemical etching with the assistance of silver nanoparticles. Dark and light volt-ampere (I – V) characteristics of the heterojunctions under study were measured, the value of the potential barrier height, the values of the serial R_s and the shunt R_sh resistance at room temperature were determined. It was established that the silicon surface treatment does not affect the potential barrier height, but significantly affects the values of serial R_s and shunt R_sh resistance. The electrical and photoelectric properties of the obtained structures were investigated, the dominant mechanisms of current transfer through the heterostructures under forward bias are well described in the framework of emission-recombination and tunneling models with the presence of interface states. The main mechanism for the charge carrier transport through heterojunctions with the reverse bias is the Frenkel–Pool emission. Investigation of photoelectric properties of heterojunctions MoO_x/n-Si was carried out at illumination by white light with intensity P_opt = 80 mW/сm². It was established that the heterostructure No.5 MoO_x/n-Si with grown nanowires and etched silver nanoparticles has a maximum open-circuit voltage V_oc = 0.17 V, short-circuit current density I_sc = 10 mA/cm². The possibilities of using the obtained heterostructures as photodiodes were analyzed.