UV to NIR photodetection in lateral homojunction PN diode of WSe2 achieved via IGZO sputtering†

Abstract

Nano-devices based on two-dimensional (2D) semiconductor materials encourage the development of high-performance homogeneous junctions owing to their remarkable electronic and optoelectronic properties. Herein, we fabricated an atomically thin WSe₂ (∼4.8 nm) lateral homojunction PN diode through the deposition of indium gallium zinc oxide (IGZO) via sputtering. Pristine WSe₂ exhibited dominant p-type semiconductor behavior, while IGZO-deposited WSe₂ demonstrated n-type behavior, revealing that IGZO altered the carrier polarity of WSe₂ from p- to n-type. Furthermore, we investigated gate-dependent I–V curves of the lateral homojunction PN (p-WSe₂/n-IGZO·WSe₂) diode in the dark based on a single WSe₂ flake, which showed a promising current rectification ratio (∼1.6 × 10⁴) and ideality factor (∼1.23) at V_BG = −30 V, respectively. Subsequently, to explore the photodiode characteristics, we irradiated the lateral homojunction PN diode of WSe₂ under ultra-violet (UV) to near-infrared (NIR) light (365, 530, and 850 nm). The I–V curves of the diode significantly changed under light irradiation, and the open circuit voltage (V_oc = 202, 166, and 134 mV) and short circuit current (I_sc = 320, 171, and 122 nA) values increased under illumination of a laser of small wavelength (365, 530, and 850 nm). Furthermore, we investigated the time-dependent photoresponse behavior of the diode under different laser lights. This demonstrated promising photoresponsivity (R_Ph = 40.1 A W⁻¹) and external quantum efficiency (EQE = 13 634%) at λ = 365 nm and V_BG = 15 V. Hence, our lateral homojunction PN diode WSe₂–IGZO/WSe₂ shows great potential for next-generation electronic devices at the nanoscale level.