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Title: Radiation-induced direct bandgap transition in few-layer MoS 2

Abstract

We report photoluminescence (PL) spectroscopy of air-suspended and substrate-supported molybdenum disulfide (MoS 2) taken before and after exposure to proton radiation. For 2-, 3-, and 4-layer MoS 2, the radiation causes a substantial (>10×) suppression of the indirect bandgap emission, likely due to a radiation-induced decoupling of the layers. For all samples measured (including the monolayer), we see the emergence of a defect-induced shoulder peak at around 1.7 eV, which is redshifted from the main direct bandgap emission at 1.85 eV. Here, defects induced by the radiation trap the excitons and cause them to be redshifted from the main direct band emission. After annealing, the defect-induced sideband disappears, but the indirect band emission remains suppressed, indicating a permanent transition into a direct bandgap material. While suspended 2-, 3-, and 4-layer MoS 2 show no change in the intensity of the direct band emission after radiation exposure, substrate-supported MoS 2 exhibits an approximately 2-fold increase in the direct bandgap emission after irradiation. Suspended monolayer MoS 2 shows a 2–3× drop in PL intensity; however, substrate-supported monolayer MoS 2 shows a 2-fold increase in the direct band emission.

Authors:
 [1];  [1];  [1];  [2];  [2]; ORCiD logo [1]
  1. Univ. of Southern California, Los Angeles, CA (United States)
  2. The Aerospace Corporation, El Segundo, CA (United States)
Publication Date:
Research Org.:
Univ. of Southern California, Los Angeles, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1535349
Alternate Identifier(s):
OSTI ID: 1395188
Grant/Contract Number:  
FG02-07ER46376
Resource Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 111; Journal Issue: 13; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Physics

Citation Formats

Wang, Bo, Yang, Sisi, Chen, Jihan, Mann, Colin, Bushmaker, Adam, and Cronin, Stephen B. Radiation-induced direct bandgap transition in few-layer MoS2. United States: N. p., 2017. Web. doi:10.1063/1.5005121.
Wang, Bo, Yang, Sisi, Chen, Jihan, Mann, Colin, Bushmaker, Adam, & Cronin, Stephen B. Radiation-induced direct bandgap transition in few-layer MoS2. United States. doi:10.1063/1.5005121.
Wang, Bo, Yang, Sisi, Chen, Jihan, Mann, Colin, Bushmaker, Adam, and Cronin, Stephen B. Wed . "Radiation-induced direct bandgap transition in few-layer MoS2". United States. doi:10.1063/1.5005121. https://www.osti.gov/servlets/purl/1535349.
@article{osti_1535349,
title = {Radiation-induced direct bandgap transition in few-layer MoS2},
author = {Wang, Bo and Yang, Sisi and Chen, Jihan and Mann, Colin and Bushmaker, Adam and Cronin, Stephen B.},
abstractNote = {We report photoluminescence (PL) spectroscopy of air-suspended and substrate-supported molybdenum disulfide (MoS2) taken before and after exposure to proton radiation. For 2-, 3-, and 4-layer MoS2, the radiation causes a substantial (>10×) suppression of the indirect bandgap emission, likely due to a radiation-induced decoupling of the layers. For all samples measured (including the monolayer), we see the emergence of a defect-induced shoulder peak at around 1.7 eV, which is redshifted from the main direct bandgap emission at 1.85 eV. Here, defects induced by the radiation trap the excitons and cause them to be redshifted from the main direct band emission. After annealing, the defect-induced sideband disappears, but the indirect band emission remains suppressed, indicating a permanent transition into a direct bandgap material. While suspended 2-, 3-, and 4-layer MoS2 show no change in the intensity of the direct band emission after radiation exposure, substrate-supported MoS2 exhibits an approximately 2-fold increase in the direct bandgap emission after irradiation. Suspended monolayer MoS2 shows a 2–3× drop in PL intensity; however, substrate-supported monolayer MoS2 shows a 2-fold increase in the direct band emission.},
doi = {10.1063/1.5005121},
journal = {Applied Physics Letters},
number = 13,
volume = 111,
place = {United States},
year = {2017},
month = {9}
}

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Works referenced in this record:

Atomically Thin MoS2 A New Direct-Gap Semiconductor
journal, September 2010