Modulation of Schottky Barrier Height by Nitrogen Doping and Its Influence on Responsivity of Monolayer MoS₂ Photodetector

Abstract

Abstract Monolayer MoS 2 flakes are prepared by low‐pressure chemical vapor deposition on p‐type and n‐type silicon substrates and post‐treated under nitrogen (N 2 )‐rich conditions to incorporate nitrogen atoms in sulfur vacancies. Ultraviolet photoelectron spectroscopy (UPS) shows an increase in work function value by 0.47 eV and 0.53 eV compared to undoped MoS 2 when grown on p and n‐type substrates, respectively. Photodetection experiments conducted for doped and undoped MoS 2 grown on p‐type substrate reveal a decrease in the value of photo responsivity for N 2 doped MoS 2 (191 A W −1 ) compared with undoped MoS 2 (572 A W −1 ). Also, MoS 2 crystals grown and doped on an n‐type substrate display an important enhancement of the photoresponsivity from 63 A W −1 for undoped to 606 A W −1 for N 2 doped MoS 2 . The modulation of Schottky barrier height for N 2 doped MoS 2 on p type substrate decreased whereas for n type substrate the high electric field created due to the difference in the Fermi level allows for greater separation of photogenerated charge carriers. This modulation in the photoresponsivity due to the selection of the type of substrate opens up new avenues of research and engineering of atomically thin optoelectronic devices.