skip to main content

Title: Gate-modulated conductance of few-layer WSe{sub 2} field-effect transistors in the subgap regime: Schottky barrier transistor and subgap impurity states

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) WSe{sub 2} 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 × 10{sup 13}/cm{sup 2}/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.
Authors:
;  [1] ; ;  [2] ;  [3] ; ;  [4] ;  [1] ;  [5] ;  [5] ;  [1] ;  [5] ;  [5] ;  [5] ;  [1] ;  [5]
  1. Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)
  2. National High Magnetic Field Lab, Florida State University, Tallahassee, Florida 32310 (United States)
  3. Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)
  4. National Institute for Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan)
  5. (United States)
Publication Date:
OSTI Identifier:
22398897
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 106; Journal Issue: 15; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; APPROXIMATIONS; CARRIER DENSITY; CARRIER MOBILITY; COMPUTERIZED SIMULATION; CRYSTAL DEFECTS; DENSITY OF STATES; DIFFUSION BARRIERS; ENERGY GAP; EV RANGE; FIELD EFFECT TRANSISTORS; FIELD EMISSION; IMPURITIES; LAYERS; SEMICONDUCTOR MATERIALS; SUBSTRATES; TEMPERATURE RANGE 0273-0400 K; TRANSITION ELEMENTS