Interface trap density in ITO/Si Schottky junction photodetectors

Abstract

Interface trapping is a notorious effect that is known to limit the performance of Schottky junction photodetectors. In this paper, the interface traps and mobility mechanism of silicon Schottky junction photodetectors were studied with two different electrode structures, namely, field and Schottky structures. The dark current of the devices mainly originated from the junction area-dependent dark current. The characteristic tunneling energies of the devices with field and Schottky structures were 0.095 and 0.102eV, respectively, and their activation energies were 0.193 and 0.294eV, respectively, which are less than half the band gap of silicon. These values are consistent with the devices displaying a trap-assisted tunneling (TAT) mechanism. An equivalent circuit model of metal–insulator–semiconductor interface traps was constructed. The interface trap densities of the devices with field and Schottky structures were calculated to be 1.37 × 10¹⁰ and 3.96 × 10¹¹/(cm²∙eV), respectively. Thus, the field structure can effectively suppress the current arising from trap-assisted tunneling.