Electric-Field-Controlled Optical Response in Vertical Gr/WSe2/SnSe2 Heterojunction Photodetectors

Abstract

Electrically tunable spectral responses in two-dimensional transition metal dichalcogenides (TMDs) heterostructures are highly promising for miniaturized spectrometers. However, strong exciton binding energy and challenges in achieving effective spectral modulation limit their performance. Here, we demonstrate enhanced exciton ionization assisted by out-of-plane electric fields, along with spectral response modulation in vertical Gr/WSe2/SnSe2. The bottom monolayer graphene electrode, with minimal electrostatic screening, enables gate modulation of the WSe2 channel. The applied out-of-plane electric fields, generated through gate and drain bias, coupled with a short physical length, not only modulate the spectral response through the Stark shift and F–K-type field-induced modulation but also enhance the carrier dissociation rate, enabling a high responsivity of 260 mA W–1, rapid response times of 1 μs at Vds = −1 V. Our research holds significant potential for developing devices requiring spectral modulation, such as miniaturized computational spectrometers, with enhanced performance.