pISSN 0374-4914 eISSN 2289-0041

## Research Paper

New Phys.: Sae Mulli 2019; 69: 601-605

Published online June 28, 2019 https://doi.org/10.3938/NPSM.69.601

## Dependence of the Selective Doping Effect in Heterogeneous Defect Domains of Hexagonal-WS$_2$ on Wet-Transfer Methods

Su-Jin KIM, Hyun-Seok LEE*

Department of Physics, Chungbuk National University, Cheongju 28644, Korea

Correspondence to:hsl@chungbuk.ac.kr

Received: April 26, 2019; Revised: May 8, 2019; Accepted: May 8, 2019

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

### Abstract

Monolayer WS$_2$ grown by using chemical vapor deposition typically has a triangular or hexagonal shape depending on the growth conditions. Hexagonal (h-) WS$_2$ flakes consist of alternating heterogeneous defect domains, S vacancy (SV) and W vacancy (WV) domains, in a single monolayer crystal. Here, we investigate the wet-solution-dependent doping effects in each defect domain of h-WS$_2$ during wet transfer processes where deionized (DI) water and diluted NaOH and HF solutions are used. After transferring h-WS$_2$ on SiO$_2$/Si in each solution, we compare photoluminescence (PL)/ Raman spectra and mapping images measured by using confocal microscopy. While compared to the HF-transfer case the PL intensity of the WV domain in the DI-water-transfer case increases prominently, that of the SV domain in the NaOH-transfer case increase, but not so prominently. In comparison to the HF-transfer case, a prominently trion peak develops in the PL spectrum of the SV domain for the NaOH-transfer case, moreover, the strain- and doping-related peaks in the Raman spectra of the SV and the WV domains are red shifted. During the NaOH-solution-transfer process, OH$^-$ ions attached to SVs result in electron doping effect selectively for the SV domain.

Keywords: Tungsten diselenide, Chemical vapor deposition, Wet transfer, Photoluminescence, Raman spectroscopy