Local Electronic Structure Changes in Polycrystalline CdTe with CdCl2 Treatment and Air Exposure
Abstract
Postdeposition CdCl2 treatment of polycrystalline CdTe is known to increase the photovoltaic device efficiency. However, the precise chemical, structural, and electronic changes that underpin this improvement are still debated. In this work, spectroscopic photoemission electron microscopy was used to spatially map the vacuum level and ionization energy of CdTe films, enabling the identification of electronic structure variations between grains and grain boundaries (GBs). In vacuo preparation and inert transfer of oxide-free CdTe surfaces isolated the separate effects of CdCl2 treatment and ambient oxygen exposure. Qualitatively, grain boundaries displayed lower work function and downward band bending relative to grain interiors, but only after air exposure of CdCl2-treated CdTe. Analysis of numerous space charge regions at grain boundaries showed an average depletion width of 290 nm and an average band bending magnitude of 70 meV, corresponding to a GB trap density of 1011 cm–2 and a net carrier density of 1015 cm–3. Finally, these results suggest that both CdCl2 treatment and oxygen exposure may be independently tuned to enhance the CdTe photovoltaic performance by engineering the interface and bulk electronic structure.
- Authors:
-
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Colorado State Univ., Fort Collins, CO (United States). Department of Mechanical Engineering
- Publication Date:
- Research Org.:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Org.:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office; USDOE Office of Science (SC)
- OSTI Identifier:
- 1441464
- Report Number(s):
- SAND-2018-2059J
Journal ID: ISSN 1944-8244; 662903
- Grant/Contract Number:
- AC04-94AL85000; FOA-0000654; NA0003525
- Resource Type:
- Journal Article: Accepted Manuscript
- Journal Name:
- ACS Applied Materials and Interfaces
- Additional Journal Information:
- Journal Volume: 10; Journal Issue: 11; Journal ID: ISSN 1944-8244
- Publisher:
- American Chemical Society (ACS)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 36 MATERIALS SCIENCE; CdTe; grain boundaries; local electronic structure; photoemission electron microscopy; photovoltaics
Citation Formats
Berg, Morgann, Kephart, Jason M., Munshi, Amit, Sampath, Walajabad S., Ohta, Taisuke, and Chan, Calvin. Local Electronic Structure Changes in Polycrystalline CdTe with CdCl2 Treatment and Air Exposure. United States: N. p., 2018.
Web. doi:10.1021/acsami.7b18963.
Berg, Morgann, Kephart, Jason M., Munshi, Amit, Sampath, Walajabad S., Ohta, Taisuke, & Chan, Calvin. Local Electronic Structure Changes in Polycrystalline CdTe with CdCl2 Treatment and Air Exposure. United States. https://doi.org/10.1021/acsami.7b18963
Berg, Morgann, Kephart, Jason M., Munshi, Amit, Sampath, Walajabad S., Ohta, Taisuke, and Chan, Calvin. 2018.
"Local Electronic Structure Changes in Polycrystalline CdTe with CdCl2 Treatment and Air Exposure". United States. https://doi.org/10.1021/acsami.7b18963. https://www.osti.gov/servlets/purl/1441464.
@article{osti_1441464,
title = {Local Electronic Structure Changes in Polycrystalline CdTe with CdCl2 Treatment and Air Exposure},
author = {Berg, Morgann and Kephart, Jason M. and Munshi, Amit and Sampath, Walajabad S. and Ohta, Taisuke and Chan, Calvin},
abstractNote = {Postdeposition CdCl2 treatment of polycrystalline CdTe is known to increase the photovoltaic device efficiency. However, the precise chemical, structural, and electronic changes that underpin this improvement are still debated. In this work, spectroscopic photoemission electron microscopy was used to spatially map the vacuum level and ionization energy of CdTe films, enabling the identification of electronic structure variations between grains and grain boundaries (GBs). In vacuo preparation and inert transfer of oxide-free CdTe surfaces isolated the separate effects of CdCl2 treatment and ambient oxygen exposure. Qualitatively, grain boundaries displayed lower work function and downward band bending relative to grain interiors, but only after air exposure of CdCl2-treated CdTe. Analysis of numerous space charge regions at grain boundaries showed an average depletion width of 290 nm and an average band bending magnitude of 70 meV, corresponding to a GB trap density of 1011 cm–2 and a net carrier density of 1015 cm–3. Finally, these results suggest that both CdCl2 treatment and oxygen exposure may be independently tuned to enhance the CdTe photovoltaic performance by engineering the interface and bulk electronic structure.},
doi = {10.1021/acsami.7b18963},
url = {https://www.osti.gov/biblio/1441464},
journal = {ACS Applied Materials and Interfaces},
issn = {1944-8244},
number = 11,
volume = 10,
place = {United States},
year = {Mon Mar 12 00:00:00 EDT 2018},
month = {Mon Mar 12 00:00:00 EDT 2018}
}
Web of Science
Works referenced in this record:
Correlation of stability to varied CdCl2 treatment and related defects in CdS/CdTe PV devices as measured by thermal admittance spectroscopy
journal, November 2005
- Enzenroth, R. Albert; Barth, K. L.; Sampath, W. S.
- Journal of Physics and Chemistry of Solids, Vol. 66, Issue 11
The Nanometer-Resolution Local Electrical Potential and Resistance Mapping of CdTe Thin Films
journal, October 2013
- Jiang, C. -S.; Moutinho, H. R.; Dhere, R. G.
- IEEE Journal of Photovoltaics, Vol. 3, Issue 4
How Polycrystalline Devices Can Outperform Single-Crystal Ones: Thin Film CdTe/CdS Solar Cells
journal, June 2004
- Visoly-Fisher, I.; Cohen, S. R.; Ruzin, A.
- Advanced Materials, Vol. 16, Issue 11
Grain-Boundary-Enhanced Carrier Collection in CdTe Solar Cells
journal, April 2014
- Li, Chen; Wu, Yelong; Poplawsky, Jonathan
- Physical Review Letters, Vol. 112, Issue 15
Grain boundaries in CdTe thin film solar cells: a review
journal, July 2016
- Major, Jonathan D.
- Semiconductor Science and Technology, Vol. 31, Issue 9
Nanoscale imaging and spectroscopy of band gap and defects in polycrystalline photovoltaic devices
journal, January 2017
- Yoon, Yohan; Chae, Jungseok; Katzenmeyer, Aaron M.
- Nanoscale, Vol. 9, Issue 23
Solar cell efficiency tables (version 47): Solar cell efficiency tables
journal, November 2015
- Green, Martin A.; Emery, Keith; Hishikawa, Yoshihiro
- Progress in Photovoltaics: Research and Applications, Vol. 24, Issue 1
The Effect of Cadmium Chloride Treatment on Close-Spaced Sublimated Cadmium Telluride Thin-Film Solar Cells
journal, October 2013
- Abbas, A.; West, G. D.; Bowers, J. W.
- IEEE Journal of Photovoltaics, Vol. 3, Issue 4
Effects of oxidation and CdCl2 treatment on the electronic properties of CdTe polycrystalline films
journal, September 2015
- Lv, Bin; Huang, Lei; Fu, Min
- Materials Chemistry and Physics, Vol. 165
Time-resolved photoluminescence studies of CdTe solar cells
journal, September 2003
- Metzger, W. K.; Albin, D.; Levi, D.
- Journal of Applied Physics, Vol. 94, Issue 5, p. 3549-3555
The effect of MoOx inter-layer on thin film CdTe/CdS solar cell
journal, October 2012
- Irfan, Irfan; Lin, Hao; Xia, Wei
- Solar Energy Materials and Solar Cells, Vol. 105
Structural and chemical interface characterization of CdTe solar cells by transmission electron microscopy
journal, May 2003
- Terheggen, M.; Heinrich, H.; Kostorz, G.
- Thin Solid Films, Vol. 431-432
Influence of the growth conditions and postdeposition treatments upon the grain boundary barrier height of CdTe thin films deposited by close space vapor transport
journal, October 2001
- Vigil-Galán, Osvaldo; Vaillant, Lı́dice; Mendoza-Pérez, Rogelio
- Journal of Applied Physics, Vol. 90, Issue 7
Long carrier lifetimes in large-grain polycrystalline CdTe without CdCl2
journal, June 2016
- Jensen, S. A.; Burst, J. M.; Duenow, J. N.
- Applied Physics Letters, Vol. 108, Issue 26
The electrical properties of polycrystalline silicon films
journal, December 1975
- Seto, John Y. W.
- Journal of Applied Physics, Vol. 46, Issue 12
Spatially resolved measurements of charge carrier lifetimes in CdTe solar cells
journal, March 2013
- Kraft, C.; Hempel, H.; Buschmann, V.
- Journal of Applied Physics, Vol. 113, Issue 12
Electrical activity at grain boundaries of thin films
journal, January 2005
- Fuertes Marrón, D.; Sadewasser, S.; Meeder, A.
- Physical Review B, Vol. 71, Issue 3
Layer dependence of the electronic band alignment of few-layer on measured using photoemission electron microscopy
journal, June 2017
- Berg, Morgann; Keyshar, Kunttal; Bilgin, Ismail
- Physical Review B, Vol. 95, Issue 23
Scanning Kelvin probe measurements on As-doped CdTe solar cells
journal, September 2013
- Brooks, W. S. M.; Irvine, S. J. C.; Taylor, D. M.
- Semiconductor Science and Technology, Vol. 28, Issue 10
In-depth analysis of chloride treatments for thin-film CdTe solar cells
journal, October 2016
- Major, J. D.; Al Turkestani, M.; Bowen, L.
- Nature Communications, Vol. 7, Issue 1
High-resolution work function imaging of single grains of semiconductor surfaces
journal, April 2002
- Sadewasser, S.; Glatzel, Th.; Rusu, M.
- Applied Physics Letters, Vol. 80, Issue 16
CdTe solar cells with open-circuit voltage breaking the 1 V barrier
journal, February 2016
- Burst, J. M.; Duenow, J. N.; Albin, D. S.
- Nature Energy, Vol. 1, Issue 3
Possible effects of oxygen in Te-rich Σ3 (112) grain boundaries in CdTe
journal, September 2012
- Feng, Chunbao; Yin, Wan-Jian; Nie, Jinlan
- Solid State Communications, Vol. 152, Issue 18
Charge transport in CdTe solar cells revealed by conductive tomographic atomic force microscopy
journal, September 2016
- Luria, Justin; Kutes, Yasemin; Moore, Andrew
- Nature Energy, Vol. 1, Issue 11
Physics of grain boundaries in polycrystalline photovoltaic semiconductors
journal, March 2015
- Yan, Yanfa; Yin, Wan-Jian; Wu, Yelong
- Journal of Applied Physics, Vol. 117, Issue 11
Correlative impurity distribution analysis in cadmium telluride (CdTe) thin-film solar cells by ToF-SIMS 2D imaging
journal, December 2016
- Mao, Dan; Blatz, Graham; Wickersham, C. E.
- Solar Energy Materials and Solar Cells, Vol. 157
Microtexture of chloride treated CdTe thin films deposited by CSS technique
journal, June 2007
- Quadros, João; Pinto, André L.; Moutinho, Hélio R.
- Journal of Materials Science, Vol. 43, Issue 2
First-principles study of oxygen-doped CdTe
journal, May 2016
- Flores, Mauricio A.; Orellana, Walter; Menéndez-Proupin, Eduardo
- Physical Review B, Vol. 93, Issue 18
Single vacuum chamber with multiple close space sublimation sources to fabricate CdTe solar cells
journal, February 2016
- Swanson, Drew E.; Kephart, Jason M.; Kobyakov, Pavel S.
- Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, Vol. 34, Issue 2
Effects of CdCl2 treatment on the recrystallization and electro-optical properties of CdTe thin films
journal, May 1998
- Moutinho, H. R.; Al-Jassim, M. M.; Levi, D. H.
- Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, Vol. 16, Issue 3
X-ray and ultraviolet photoelectron spectroscopy measurements of Cu-doped CdTe(111)-B: Observation of temperature-reversible CuxTe precipitation and effect on ionization potential
journal, August 2007
- Teeter, Glenn
- Journal of Applied Physics, Vol. 102, Issue 3
Electrical properties of grain boundaries in polycrystalline compound semiconductors
journal, February 1990
- Greuter, F.; Blatter, G.
- Semiconductor Science and Technology, Vol. 5, Issue 2
Band alignment of front contact layers for high-efficiency CdTe solar cells
journal, December 2016
- Kephart, J. M.; McCamy, J. W.; Ma, Z.
- Solar Energy Materials and Solar Cells, Vol. 157
Photoemission study of CdTe surfaces after low-energy ion treatments
conference, June 2012
- Hanks, D.; Weir, M.; Horsley, K.
- 2012 IEEE 38th Photovoltaic Specialists Conference (PVSC), 2012 38th IEEE Photovoltaic Specialists Conference
Effects of CdCl2 treatment on the local electronic properties of polycrystalline CdTe measured with photoemission electron microscopy
conference, June 2017
- Berg, Morgann; Kephart, Jason M.; Sampath, Walajabad S.
- 2017 IEEE 44th Photovoltaic Specialists Conference (PVSC), 2017 IEEE 44th Photovoltaic Specialist Conference (PVSC)
The effect of a post-activation annealing treatment on thin film cdte device performance
conference, June 2015
- Abbas, A.; Swanson, D.; Munshi, A.
- 2015 IEEE 42nd Photovoltaic Specialists Conference (PVSC), 2015 IEEE 42nd Photovoltaic Specialist Conference (PVSC)
Band alignment of front contact layers for high-efficiency CdTe solar cells
journal, December 2016
- Kephart, J. M.; McCamy, J. W.; Ma, Z.
- Solar Energy Materials and Solar Cells, Vol. 157
Kelvin probe force microscopy for the nano scale characterization of chalcopyrite solar cell materials and devices
journal, May 2003
- Sadewasser, S.; Glatzel, Th.; Schuler, S.
- Thin Solid Films, Vol. 431-432
Electrical properties of grain boundaries in polycrystalline compound semiconductors
journal, February 1990
- Greuter, F.; Blatter, G.
- Semiconductor Science and Technology, Vol. 5, Issue 2
Works referencing / citing this record:
Grain boundary passivation by CdCl2 treatment in CdTe solar cells revealed by Kelvin probe force microscopy
journal, October 2018
- Li, Chuang; Chen, Gang; Wang, Wenwu
- Journal of Materials Science: Materials in Electronics, Vol. 29, Issue 24