Sub-bandgap photoresponse and leakage current analysis in gold thin film-hyperdoped silicon photodiodes

We present a study of the sub-bandgap photoresponse and leakage current in gold-hyperdoped silicon photodiodes prepared using pulsed laser melting (PLM) of sub-nanometer gold films on n-type silicon substrates. Variable-temperature photo- and dark-current analysis provide insight into the role of PLM conditions on device performance. In general, we find photocurrent activation energies comparable to room temperature, suggesting a weak thermally-assisted optical photoresponse mechanism. Additionally, we establish a connection between repetitive PLM pulsing and increased device leakage current, which originates from electrically-active defects. Finally, we propose an explanation for the limited sub-bandgap external quantum efficiencies reported for hyperdoped silicon devices on the basis that the depletion layer largely does not encompass the hyperdoped layer where absorption occurs.

Automated summary

This study investigates the sub-bandgap photoresponse and leakage current in gold-hyperdoped silicon photodiodes prepared using pulsed laser melting. The results suggest a weak thermally-assisted optical photoresponse mechanism and establish a connection between repetitive pulsing and increased leakage current from electrically-active defects. The study also proposes an explanation for the limited sub-bandgap external quantum efficiencies reported for hyperdoped silicon devices.