On the Optoelectronic Mechanisms Ruling Ti‐hyperdoped Si Photodiodes

Abstract

Abstract This work deepens the understanding of the optoelectronic mechanisms ruling hyperdoped‐based photodevices and shows the potential of Ti hyperdoped‐Si as a fully complementary metal‐oxide semiconductor compatible material for room‐temperature infrared photodetection technologies. By the combination of ion implantation and laser‐based methods, ≈20 nm thin hyperdoped single‐crystal Si layers with a Ti concentration as high as 10 20 cm −3 are obtained. The Ti hyperdoped Si/p‐Si photodiode shows a room temperature rectification factor at ±1 V of 509. Analysis of the temperature‐dependent current–voltage characteristics shows that the transport is dominated by two mechanisms: a tunnel mechanism at low bias and a recombination process in the space charge region at high bias. A room‐temperature sub‐bandgap external quantum efficiency (EQE) extending to 2.5 µm wavelength is obtained. Temperature‐dependent spectral photoresponse behavior reveals an increase of the EQE as the temperature decreases, showing a low‐energy photoresponse edge at 0.45 eV and a high‐energy photoresponse edge at 0.67 eV. Temperature behavior of the open‐circuit voltage correlates with the high‐energy photoresponse edge. A model is proposed to relate the optoelectronic mechanisms to sub‐bandgap optical transitions involving an impurity band. This model is supported by numerical semiconductor device simulations using the SCAPS software.