IJM017 Influence of FeO Layer Thickness on Characteristics of FeO/Porous Silicon Heterojunction Photodetectors

Abstract

This work investigates the influence of iron oxide (FeO) layer thickness on the optoelectronic performance of FeO/porous silicon (PSi) heterojunction photodetectors. Devices with FeO thicknesses of 100, 200, and 300 nm were fabricated and evaluated in terms of dark current, photocurrent, sensitivity, spectral responsivity, external quantum efficiency (EQE), specific detectivity (D^*), noise-equivalent power (NEP), and temporal response. The results reveal that the FeO thickness plays a decisive role in charge transport, carrier recombination, and optical absorption. A 200 nm FeO layer exhibited optimal behavior, achieving the highest responsivity (0.55 A/W at ~550 nm), EQE (~1.25%), and detectivity (~1.0×10¹³ Jones), along with the lowest NEP (~4×10⁻¹² W). While thinner layers (100 nm) suffered from poor light absorption and incomplete passivation, thicker layers (300 nm) introduced higher series resistance and trap states, degrading performance. The findings demonstrate that precise control of FeO thickness is critical for optimizing FeO/PSi heterojunction photodetectors for visible light applications.