2015/04/13 by Junjie Wang, Daniel Rhodes, Simin Feng +7 · 29 citations
Materials Science · Physics and Astronomy · #2D Materials and Applications #Conductance #Field-effect transistor #Graphene research and applications #Impurity #Schottky barrier #Schottky diode #Semiconductor #Semiconductor materials and interfaces #Thermionic emission #Transistor #cond-mat.mes-hall
paper · pdf · doi:10.1063/1.4918282
published in Applied Physics Letters 106(15) (American Institute of Physics) · 18 pages including SI, 8 figures total
openalex publication_date 2015/04/13 · arxiv created 2015/05/04 · arxiv updated 2015/05/06 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
Two key subjects stand out in the pursuit of semiconductor research: material quality and contact technology. The fledging field of atomically thin transition metal dichalcogenides (TMDCs) faces a number of challenges in both efforts. This work attempts to establish a connection between the two by examining the gate-dependent conductance of few-layer (1-5L) WSe2 field effect devices. Measurements and modeling of the subgap regime reveal Schottky barrier transistor behavior. We show that transmission through the contact barrier is dominated by thermionic field emission (TFE) at room temperature, despite the lack of intentional doping. The TFE process arises due to a large number of subgap impurity states, the presence of which also leads to high mobility edge carrier densities. The density of states of such impurity states is self-consistently determined to be approximately 1–2 × 1013/cm2/eV in our devices. We demonstrate that substrate is unlikely to be a major source of the impurity states and suspect that lattice defects within the material itself are primarily responsible. Our experiments provide key information to advance the quality and understanding of TMDC materials and electrical devices.