Influence of electrode materials on molybdenum oxide/n-Si photodetectors

Abstract

Until recently, different metals have been adopted as the electrode materials for MoOx/Si photodetectors and solar cells, but the influence of these different metals has not been investigated. We have systematically studied and proved that the choice of metal has a great impact on optoelectronic performance. Ag and Al with similar low work functions display similar current–voltage behavior before and after the introduction of MoOx; whereas Au and Ni which own similar high work functions lead to another type of current–voltage behavior. MoOx in the metal/MoOx/Si samples brings the superior diode behavior with an enhanced responsivity and decreased dark current as compared with the metal/Si samples. The choice of Ag as the top electrode on MoOx/Si has low alloying or defect formation with the MoOx/Si structure preventing the deterioration of the diode behavior, and the large downward band bending in MoOx at the Ag/MoOx junction facilitates the multitunnelling capture emission. This leads to high responsivity while maintaining the low dark current.