Charge Redistribution in Mg-Doped p-Type MoS2/GaN Photodetectors

MoS2/GaN p–n heterojunction photodetectors with enhanced built-in electric field have paved the way for nanoelectronic and nano-optoelectronic applications. However, the realization of p-type MoS2/n-type GaN p–n heterostructures is still challenging because of the complex and unstable preparation process of p-type MoS2. Herein, Mg-doped p-type MoS2/GaN p–n heterojunctions have been synthesized via a two-step method involving electron beam evaporation and chemical vapor deposition. First-principles calculations based on density functional theory reveal that the substituted Mg atoms induce ample holes. Compared with the unintentionally doped devices, the Mg-doped p-type MoS2/GaN heterojunctions show an inverted internal electric field, a responsivity of 260 mA/W at 365 nm and 2 V, and a fast response (a rise/fall time of <20/20 ms at 365 nm and 2 V). Consequently, this study proposes an efficient strategy for preparing p-type MoS2/GaN heterojunctions for applications in nanoelectronic and nano-optoelectronic devices.