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Title: Monte Carlo simulations of disorder in ZnSn N 2 and the effects on the electronic structure

In multinary compound semiconductors, cation disorder can decisively alter the electronic properties and impact potential applications. ZnSnN 2 is a ternary nitride of interest for photovoltaics, which forms in a wurtzite-derived crystal structure. In the ground state, every N anion is coordinated by two Zn and two Sn cations, thereby observing the octet rule locally. Using a motif-based model Hamiltonian, we performed Monte Carlo simulations that provide atomistic representations of ZnSnN 2 with varying degrees of cation disorder. Subsequent electronic structure calculations describe the evolution of band gaps, optical properties, and carrier localization effects as a function of the disorder. We find that octet-rule conserving disorder is practically impossible to avoid but perfectly benign, with hardly any effects on the electronic structure. In contrast, a fully random cation distribution would be very detrimental, but fortunately it is energetically highly unfavorable. A degree of disorder that can realistically be expected for nonequilibrium thin-film deposition leads to a moderate band-gap reduction and to moderate carrier localization effects. Comparing the simulated structures with experimental samples grown by sputtering, we find evidence that these samples indeed incorporate a certain degree of octet-rule violating disorder, which is reflected in the x-ray diffraction and in themore » optical absorption spectra. This study demonstrates that the electronic properties of ZnSnN 2 are dominated by changes of the local coordination environments rather than long-range ordering effects.« less
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [2] ;  [1] ;  [2]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States); Colorado School of Mines, Golden, CO (United States)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Report Number(s):
NREL/JA-5K00-68918
Journal ID: ISSN 2475-9953; PRMHAR; TRN: US1800756
Grant/Contract Number:
AC36-08GO28308; AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Physical Review Materials
Additional Journal Information:
Journal Volume: 1; Journal Issue: 3; Journal ID: ISSN 2475-9953
Publisher:
American Physical Society (APS)
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; photovoltaics; electronic structure; Monte Carlo simulation
OSTI Identifier:
1415121
Alternate Identifier(s):
OSTI ID: 1374771