Phase transition in WSe2(1-x)Te2x alloys and their application in field effect transistor

• Main Author: Le, Quang Luan
• Other Authors: Liu Zheng
• Format: Final Year Project
• Language: English
• Published: 2015
• Subjects: DRNTU::Engineering::Materials
• Online Access: http://hdl.handle.net/10356/62998
• Institution: Nanyang Technological University

Alloying of transition metal dichalcogenides is a promising approach to create materials suitable for electronic applications. WSe2 and WTe2 are from group 6 transition metal dichalcogenides and possess different structure of 2H and distorted 1T respectively. In this work, single crystals of WSe2(1-x)Te2x alloys (0 ≤ x ≤ 1) were successfully synthesized by chemical vapor transport while WSe2 and WTe2 were two ends of the alloy spectrum. The crystal structure of alloys depended on values of x. The alloys exhibited 2H structure for x ranged within 0-0.6 and distorted 1T structure for x values of 0.5-1. There was a shift in crystal structure from 2H to distorted 1T when x increased from 0 to 1 with a transition zone at the range of 0.5-0.6. In addition, 2H WSe2(1-x)Te2x alloys showed decrease in bandgap with increasing of x, which opened the possibility of bandgap controlling. Moreover, FET device based on few layer 2H WSe2(1-x)Te2x alloys showed Ion/Ioff ratio of 103 and charge mobility of 11.5 cm2V-1s-1; thus indicating its feasibility for application in FET and other nanoelectronics devices.