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Title: Near-Surface [Ga]/([In]+[Ga]) Composition in Cu(In,Ga)Se 2 Thin-Film Solar Cell Absorbers: An Overlooked Material Feature

Abstract

The chemical and electronic structures in the near-surface region of Cu(In,Ga)Se 2 thin-film solar cell absorbers are investigated using nondestructive soft and hard X-ray photoelectron spectroscopy. In addition to a pronounced surface Cu-depletion, the [Ga]/([In]+[Ga]) composition indicates that the topmost surface is Ga-poor (or In-rich). For the studied depth region, common depth profiling techniques generally fail to provide reliable information and, thus, the near-surface chemical and electronic structure profiles are often overlooked. The relation between the observed near-surface elemental compositions and the derived electronic properties of the absorber material is discussed. It is found that the surface band gap energy crucially depends on the Cu-deficiency of the absorber surface and suggests that it is, in this region, only secondarily determined by the [Ga]/([In]+[Ga]) ratio.

Authors:
ORCiD logo [1];  [2];  [2];  [2];  [2];  [3];  [4];  [3];  [4];  [5];  [6];  [1];  [1]
  1. Helmholtz-Zentrum Berlin (HZB), Berlin (Germany). German Research Centre for Materials and Energy
  2. Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW), Stuttgart (Germany)
  3. National Inst. for Materials Science (NIMS) Tsukuba (Japan)
  4. Synchrotron X-ray Station at SPring-8National Inst. for Materials Science (NIMS), Hyogo (Japan)
  5. Japan Atomic Energy Agency (JAEA), Hyogo (Japan)
  6. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; Helmholtz-Association; German Academic Exchange Agency
OSTI Identifier:
1601208
Grant/Contract Number:  
[AC02-05CH11231; 331 4 04 002; VH-NG-423]
Resource Type:
Accepted Manuscript
Journal Name:
Physica Status Solidi. A, Applications and Materials Science
Additional Journal Information:
[ Journal Volume: 216; Journal Issue: 18]; Journal ID: ISSN 1862-6300
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; chalcopyrites; thin-film solar cells; surface band gap; photoemission spectroscopy

Citation Formats

Félix, Roberto, Witte, Wolfram, Hariskos, Dimitrios, Paetel, Stefan, Powalla, Michael, Lozac'h, Mickael, Ueda, Shigenori, Sumiya, Masatomo, Yoshikawa, Hideki, Kobayashi, Keisuke, Yang, Wanli, Wilks, Regan G., and Bär, Marcus. Near-Surface [Ga]/([In]+[Ga]) Composition in Cu(In,Ga)Se2 Thin-Film Solar Cell Absorbers: An Overlooked Material Feature. United States: N. p., 2019. Web. doi:10.1002/pssa.201800856.
Félix, Roberto, Witte, Wolfram, Hariskos, Dimitrios, Paetel, Stefan, Powalla, Michael, Lozac'h, Mickael, Ueda, Shigenori, Sumiya, Masatomo, Yoshikawa, Hideki, Kobayashi, Keisuke, Yang, Wanli, Wilks, Regan G., & Bär, Marcus. Near-Surface [Ga]/([In]+[Ga]) Composition in Cu(In,Ga)Se2 Thin-Film Solar Cell Absorbers: An Overlooked Material Feature. United States. doi:10.1002/pssa.201800856.
Félix, Roberto, Witte, Wolfram, Hariskos, Dimitrios, Paetel, Stefan, Powalla, Michael, Lozac'h, Mickael, Ueda, Shigenori, Sumiya, Masatomo, Yoshikawa, Hideki, Kobayashi, Keisuke, Yang, Wanli, Wilks, Regan G., and Bär, Marcus. Wed . "Near-Surface [Ga]/([In]+[Ga]) Composition in Cu(In,Ga)Se2 Thin-Film Solar Cell Absorbers: An Overlooked Material Feature". United States. doi:10.1002/pssa.201800856.
@article{osti_1601208,
title = {Near-Surface [Ga]/([In]+[Ga]) Composition in Cu(In,Ga)Se2 Thin-Film Solar Cell Absorbers: An Overlooked Material Feature},
author = {Félix, Roberto and Witte, Wolfram and Hariskos, Dimitrios and Paetel, Stefan and Powalla, Michael and Lozac'h, Mickael and Ueda, Shigenori and Sumiya, Masatomo and Yoshikawa, Hideki and Kobayashi, Keisuke and Yang, Wanli and Wilks, Regan G. and Bär, Marcus},
abstractNote = {The chemical and electronic structures in the near-surface region of Cu(In,Ga)Se2 thin-film solar cell absorbers are investigated using nondestructive soft and hard X-ray photoelectron spectroscopy. In addition to a pronounced surface Cu-depletion, the [Ga]/([In]+[Ga]) composition indicates that the topmost surface is Ga-poor (or In-rich). For the studied depth region, common depth profiling techniques generally fail to provide reliable information and, thus, the near-surface chemical and electronic structure profiles are often overlooked. The relation between the observed near-surface elemental compositions and the derived electronic properties of the absorber material is discussed. It is found that the surface band gap energy crucially depends on the Cu-deficiency of the absorber surface and suggests that it is, in this region, only secondarily determined by the [Ga]/([In]+[Ga]) ratio.},
doi = {10.1002/pssa.201800856},
journal = {Physica Status Solidi. A, Applications and Materials Science},
number = [18],
volume = [216],
place = {United States},
year = {2019},
month = {6}
}

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