Annealing Temperature Effect on the Surface Properties of the MoSe Thin Films

Abstract

Two‐dimensional transition metal dichalcogenides have been studied extensively in the field of electronics and photonics. Among them, the molybdenum chalcogenides have been receiving considerable attention due to their potential usage in field effect transistors and biosensors. Despite such promising aspects of these materials, studies regarding temperature effects on MoSe remain relatively rare. In this paper, MoxSey (x = 0∽10, y = 0∽2) thin films were fabricated by radio frequency (RF) magnetron co‐sputtering on silicon substrates and investigated using scanning electron microscopy for various atomic ratios and annealing temperatures ranging from room temperature to 500 oC. Above the melting point of Se (217 oC), Se particles evaporated and formed a layer subsequently leading Mo particles to be exposed on the surface of the thin films. From the X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS) results, silicon peaks from the substrate were observed due to the evaporation of Se particles. In addition, both Mo and Se were oxidized at temperatures above 300 oC. The work function (WF) of the MoxSey thin films showed the highest value at 200 oC, which was measured by ultra‐violet photoelectron spectroscopy (UPS) and a Kelvin probe. Above the melting point of Se, there was a tendency for the work function to decrease due to the influence of Mo.This article is protected by copyright. All rights reserved.

Etching and Compositional Ratio Effect on the Surface Properties of Bismuth Telluride Thin Films

“…This evolution indicates that the atomic ratio of the chemical species of different oxidation states for each element changed drastically. In order to obtain the detailed chemical information of Bi, Te and O, the narrow XPS spectra were deconvoluted with XPS peak4.1 and the detailed fitting parameters are described elsewhere [20]. To avoid the complexity during the peak fitting process due to the large spin orbit-splitting constants of Bi 4f (5.4 eV) and Te 3d (10.4 eV) [27,28], Bi 4f 7/2 and Te 3d 5/2 peaks were deconvoluted instead of the whole Bi 4f and Te 3d peaks.…”

“…Specifically, the RF magnetron co-sputtering method can easily adjust the atomic composition ratio by sending different powers to the two targets. Furthermore, the technique provides advantages such as high deposition rates and excellent adhesion between the TF material and substrate [20]. Thus, bismuth telluride TFs of various Te composition ratios were fabricated using the RF magnetron co-sputtering method and the resulting TFs were used as a platform to probe the surface properties in this work.…”