Fabry-Pérot Interference Enhanced GaSe Visible-blind UV Photodetectors

Abstract

In this letter, we reported the fabrication of an asymmetric Fabry-Pérot (F-P) structure by planar stacking of GaSe nanosheet, Al2O3 spacer and Al back reflector. For the selective absorption enhancement in UV region, the Al2O3 thickness was optimized to be 91 nm by Finite-difference time-domain (FDTD) solution. Compared with the device without the asymmetric F-P structure, responsivity (R) and photoconductive gain (G) of the device was improved by one order of magnitude, giving a highest response at 265 nm illumination and the values of 1.08 A/W and 5.05 at the weak light intensity of 20 μW/cm2, respectively. The UV-to-visible rejection ratio (R265/R430) was also improved from 2.7 to 10.9, revealing the wavelength-selective absorption enhancement in UV region. This work offers a promising strategy for high-performance UV photodetectors with potential application in the new-generation market for miniaturized, bendable, and wearable devices.