Differentiation of ultraviolet/visible photons from near infrared photons by MoS2/GaN/Si-based photodetector

Conventional photodetectors (PDs) generally exhibit a unipolar photoresponse within their responsive spectral range. Different from the traditional PDs, we report here a broadband PD based on the MoS2/GaN/Si heterojunction that shows a unique phenomenon of wavelength selectivity through photocurrent polarity inversion. Overall, the device can differentiate the photons of the ultraviolet (UV)/visible region from that of the near infrared (NIR) region. This polarity inversion is explained with the help of the band diagram and the wavelength dependent photothermoelectric (PTE) effect in MoS2. The vertical transport characteristics of the MoS2/GaN/Si device exhibit a high spectral response in a broad range of wavelengths (300–1100 nm) in a self-biased mode. The maximum response of the device is found to be 23.81 A/W at a wavelength of 995 nm. Our results demonstrate a route for the development of PDs without filter that possess a lot of potential for the futuristic photonic devices.