Substrate effects in high gain, low operating voltage SnSe₂ photoconductor.

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• High gain photoconductive devices are crucial for low-intensity light detection.
• Ultra-thin layered materials offer potential but often require high operating voltages and suffer from substrate effects.
• Existing planar 2D structures face challenges with responsivity and substrate-induced traps.

Purpose of the Study:

• To investigate multi-layer tin diselenide (SnSe2) based photoconductive devices.
• To compare the performance of substrate-supported interdigitated electrode (IDE) and suspended channel structures.
• To understand the role of the channel-substrate interface in device gain and performance.

Main Methods:

• Fabrication of two distinct device structures: SiO2 substrate supported IDE and suspended channel.
• Characterization of responsivity and transient response under varying operating voltages.
• Analysis of device performance to elucidate the impact of the channel-substrate interface.

Main Results:

• The IDE device demonstrated high responsivity (e.g., 10³ A W^-1 at 1 mV) at ultra-low voltages, outperforming existing planar 2D structures.
• The suspended device showed a significant decrease in responsivity (over two orders of magnitude) but improved transient response.
• The findings highlight the critical influence of the channel-substrate interface on photoconductive gain mechanisms.

Conclusions:

• SnSe2 based devices offer promising solutions for highly sensitive, ultra-low power photoconductive applications.
• The study provides a generic methodology for evaluating intrinsic material behavior in layered photoconductors.
• Understanding channel-substrate interactions is key to optimizing future photodetector designs.