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Title: Spatially Resolved Photoexcited Charge-Carrier Dynamics in Phase-Engineered Monolayer MoS2

A fundamental understanding of the intrinsic optoelectronic properties of atomically thin transition metal dichalcogenides (TMDs) is crucial for its integration into high performance semiconductor devices. We investigate the transport properties of chemical vapor deposition (CVD) grown monolayer molybdenum disulfide (MoS2) under photo-excitation using correlated scanning photocurrent microscopy and photoluminescence imaging. We examined the effect of local phase transformation underneath the metal electrodes on the generation of photocurrent across the channel length with diffraction-limited spatial resolution. While maximum photocurrent generation occurs at the Schottky contacts of semiconducting (2H-phase) MoS2, after the metallic phase transformation (1T-phase), the photocurrent peak is observed towards the center of the device channel, suggesting a strong reduction of native Schottky barriers. Analysis using the bias and position dependence of the photocurrent indicates that the Schottky barrier heights are few meV for 1T- and ~200 meV for 2H-contacted devices. We also demonstrate that a reduction of native Schottky barriers in a 1T device enhances the photo responsivity by more than one order of magnitude, a crucial parameter in achieving high performance optoelectronic devices. The obtained results pave a pathway for the fundamental understanding of intrinsic optoelectronic properties of atomically thin TMDs where Ohmic contacts are necessary for achievingmore » high efficiency devices with low power consumption.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [1] ;  [3] ;  [3] ;  [2] ;  [1] ;  [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Rutgers Univ., Piscataway, NJ (United States)
  3. Rice Univ., Houston, TX (United States)
  4. Pacific Light Technologies, Portland, OR (United States)
Publication Date:
OSTI Identifier:
1254836
Report Number(s):
LA-UR--14-29662
Journal ID: ISSN 1936-0851
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 9; Journal Issue: 1; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society
Research Org:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE Material Science