Multilayer WSe2/MoS2 Heterojunction Phototransistors through Periodically Arrayed Nanopore Structures for Bandgap Engineering

Abstract

While 2D transition metal dichalcogenides (TMDs) are promising building blocks for various optoelectronic applications, limitations remain for multilayered TMD-based photodetectors: an indirect bandgap and a short carrier lifetime by strongly bound excitons. Accordingly, multilayered TMDs with a direct bandgap and an enhanced carrier lifetime are required for the development of various optoelectronic devices. Here, periodically arrayed nanopore structures (PANS) are proposed for improving the efficiency of multilayered p-WSe2/n-MoS2 phototransistors. Density functional theory calculations as well as photoluminescence and time-resolved photoluminescence measurements are performed to characterize the photodetector figures of merit of multilayered p-WSe2/n-MoS2 heterostructures with PANS. The characteristics of the heterojunction devices with PANS reveal an enhanced responsivity and detectivity measured under 405 nm laser excitation, which at 1.7 x 10(4) A W-1 and 1.7 x 10(13) Jones are almost two orders of magnitude higher than those of pristine devices, 3.6 x 10(2) A W-1 and 3.6 x 10(11) Jones, respectively. Such enhanced optical properties of WSe2/MoS2 heterojunctions with PANS represent a significant step toward next-generation optoelectronic applications.