Strain-Dependent Photodetection with Layered InSe Photoconductors.

Abstract

Controlled bandgap modulation is of particular interest for next generation optoelectronic devices, allowing the development of 'active' or 'reconfigurable' detectors and emitters. In van der Waals layered semiconductors, which exhibit high strain tolerance, strain has become a notable tool for active bandgap tuning. In this work, we demonstrate a flexible bulk InSe gated photoconductor with strain-induced modulation of the bandgap energy, shifting to higher and lower energies under compression and tension, respectively. Photoluminescence measurements reveal shift rates of around 117.1 meV·%^-1 in tension and 107.6 meV·%^-1 in compression. Spectral responsivity measurements indicate smaller shift rates, likely due to nonuniform strain application. Notably, these flexible devices achieve impressive performance with specific detectivities up to 3.78 × 10¹² cm·Hz^1/2·W^-1, a rise time of 4.1 μs, and a responsivity of 1.25 × 10³ A·W^-1. The realization of high responsivity and fast response times underscores the potential of this device architecture for advanced optoelectronic applications.