title: Fabrication of WS2/GaN p-n Junction by Wafer-Scale WS2Thin Film Transfer.
abstract: High quality wafer-scale free-standing WS2grown by van der Waals rheotaxy (vdWR) using Ni as a texture promoting layer is reported. The microstructure of vdWR grown WS2was significantly modified from mixture of crystallites with their c-axes both parallel to (type I) and perpendicular to (type II) the substrate to large type II crystallites. Wafer-scale transfer of vdWR grown WS2onto different substrates by an etching-free technique was demonstrated for the first time that utilized the hydrophobic property of WS2and hydrophilic property of sapphire. Our results show that vdWR is a reliable technique to obtain type-II textured crystallites in WS2, which is the key factor for the wafer-scale etching-free transfer. The transferred films were found to be free of observable wrinkles, cracks, or polymer residues. High quality p-n junctions fabricated by room-temperature transfer of the p-type WS2onto an n-type GaN was demonstrated with a small leakage current density of 29.6 μA/cm2at -1 V which shows superior performances compared to the directly grown WS2/GaN heterojunctions.
authors.affiliation: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
authors.forename: Patrick W K
authors.initials: PW
authors.lastname: Fong
authors.affiliation: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
authors.forename: Shifeng
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
authors.forename: Charles
authors.initials: C
authors.lastname: Surya