Effect of hydrogen and oxygen plasma on the photoelectronic current and photo-response time of SnS₂ flakes

Abstract

The photoelectronic properties of SnS2 flakes have been widely studied due to the abundance and environmentally friendly qualities of this material. However, the defects and residual molecules adsorbed on the SnS2 surface can have a negative influence on the photoelectronic current and photo-response time. In this paper we examine the effects of these two factors on the photoelectronic currents of SnS2 flakes. Defects on a single crystal SnS2 surface are fabricated using hydrogen and oxygen plasma and are characterized by atomic force microscopy, confocal micro-Raman spectroscopy and photoluminescence spectroscopy. Doping by oxygen plasma can be demonstrated by x-ray photoelectron spectroscopy. Both the photoelectronic current and the switching speed (on and off times) are reduced after hydrogen plasma treatment. However, oxygen plasma has two effects on SnS2 thin film transistors. First, oxygen plasma can remove the residual molecules within a short irradiation time. In this case, the photoelectronic current of SnS2 treated with oxygen plasma is enhanced several times. Second, with a longer treatment time oxygen plasma induces many defects and doping on the SnS2 flake surface, as reflected in the reduced photoelectronic current and switching speed. Results of this work have significant practical applications for photoelectronic detection with SnS2 flakes.

Improving electron mobility in MoS2 field-effect transistors by optimizing the interface contact and enhancing the channel conductance through local structural phase transition

“…The fabrication process closely resembled our previous work on SeS 2 devices. 24 Briefly, prepatterned Au electrodes were initially fabricated on a SiO 2 (285 nm)/Si (P++) substrate in an electron-beam evaporator system. Subsequently, the MoS 2 flakes with a few layers (see Fig.…”

Recent progress in plasma modification of 2D metal chalcogenides for electronic devices and optoelectronic devices

“…In fact, these two modulation strategies often co-exist, although there are differences in doping elements and regulation mechanisms. [92][93][94] In substitutional doping, pnictogen (halogen) elements, such as N, P and Cl, have been identified as suitable dopants for achieving p-type (or n-type) doping in group-VI MCs. The impurity energy levels introduced by substitutional atoms play a major role in its regulation, and defects assume a pivotal position in the doping process induced by plasma treatment using hydrogen 95 and inert elements, primarily He 96,97 and Ar.…”

Plasma Processing and Treatment of 2D Transition Metal Dichalcogenides: Tuning Properties and Defect Engineering

“…698−700 Another approach could be to implement O 2 plasma treatment for a short time. Xia et al 701 have shown that treatment of SnS 2 for 5 s with O 2 plasma effectively removes residues from the surface and enhances its photoelectric current. However, processing for longer times (e.g., 60 s) induces defects and causes oxygen doping that degrade the photoelectrical characteristics.…”

“…Surface cleaning of 2D TMDs by oxygen and water vapor may also degrade their electrical behavior and associated devices through surface passivation and/or forming unwanted oxides. − Studies have shown that the implementation of a mild plasma treatment containing nonreactive gas­(es) such as argon is effective in removing undesired species to restore electrical characteristics without etching or forming defects. − Another approach could be to implement O 2 plasma treatment for a short time. Xia et al have shown that treatment of SnS 2 for 5 s with O 2 plasma effectively removes residues from the surface and enhances its photoelectric current. However, processing for longer times (e.g., 60 s) induces defects and causes oxygen doping that degrade the photoelectrical characteristics.…”