Metal-Semiconductor Barrier Modulation for High Photoresponse in Transition Metal Dichalcogenide Field Effect Transistors

• Published in: Scientific reports Vol. 4; no. 1; p. 4041
• Main Authors: Li, Hua-Min, Lee, Dae-Yeong, Choi, Min Sup, Qu, Deshun, Liu, Xiaochi, Ra, Chang-Ho, Yoo, Won Jong
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.02.2014; Nature Publishing Group
• Subjects: 639/301/357/1018; 639/925/927/1007; Humanities and Social Sciences; multidisciplinary; Photoresponse; Science; Temperature effects; Transistors; Voltage
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep04041

A gate-controlled metal-semiconductor barrier modulation and its effect on carrier transport were investigated in two-dimensional (2D) transition metal dichalcogenide (TMDC) field effect transistors (FETs). A strong photoresponse was observed in both unipolar MoS 2 and ambipolar WSe 2 FETs (i) at the high drain voltage due to a high electric field along the channel for separating photo-excited charge carriers and (ii) at the certain gate voltage due to the optimized barriers for the collection of photo-excited charge carriers at metal contacts. The effective barrier height between Ti/Au and TMDCs was estimated by a low temperature measurement. An ohmic contact behavior and drain-induced barrier lowering (DIBL) were clearly observed in MoS 2 FET. In contrast, a Schottky-to-ohmic contact transition was observed in WSe 2 FET as the gate voltage increases, due to the change of majority carrier transport from holes to electrons. The gate-dependent barrier modulation effectively controls the carrier transport, demonstrating its great potential in 2D TMDCs for electronic and optoelectronic applications.