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Title: Thermal Stability of Hole-Selective Tungsten Oxide: In Situ Transmission Electron Microscopy Study

Abstract

In this study, the thermal stability of a contact structure featuring hole-selective tungsten oxide (WO x) and aluminum deposited onto p-type crystalline silicon (c-Si/WO x/Al) was investigated using a combination of transmission line measurements (TLM) and in situ transmission electron microscopy (TEM) studies. The TEM images provide insight into why the charge carrier transport and recombination characteristics change as a function of temperature, particularly as the samples are annealed at temperatures above 500 °C. In the as-deposited state, a ≈ 2 nm silicon oxide (SiO x) interlayer forms at the c-Si/WO x interface and a ≈ 2–3 nm aluminum oxide (AlO x) interlayer at the WO x/Al interface. When annealing above 500 °C, Al diffusion begins, and above 600 °C complete intermixing of the SiO x, WO x, AlO x and Al layers occurs. This results in a large drop in the contact resistivity, but is the likely reason surface recombination increases at these high temperatures, since a c-Si/Al contact is basically being formed. This work provides some fundamental insight that can help in the development of WOx films as hole-selective rear contacts for p-type solar cells. Furthermore, this study demonstrates that in situ TEM can provide valuable information aboutmore » thermal stability of transition metal oxides functioning as carrier-selective contacts in silicon solar cells.« less

Authors:
; ; ORCiD logo; ORCiD logo; ; ; ORCiD logo
Publication Date:
Research Org.:
Univ. of Central Florida, Orlando, FL (United States); Univ. of California, Oakland, CA (United States)
Sponsoring Org.:
USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
OSTI Identifier:
1464976
Alternate Identifier(s):
OSTI ID: 1546082
Grant/Contract Number:  
EE0007533; AC02- 05CH11231; AC02-05CH11231
Resource Type:
Published Article
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Name: Scientific Reports Journal Volume: 8 Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Country of Publication:
United Kingdom
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Ali, Haider, Koul, Supriya, Gregory, Geoffrey, Bullock, James, Javey, Ali, Kushima, Akihiro, and Davis, Kristopher O. Thermal Stability of Hole-Selective Tungsten Oxide: In Situ Transmission Electron Microscopy Study. United Kingdom: N. p., 2018. Web. doi:10.1038/s41598-018-31053-w.
Ali, Haider, Koul, Supriya, Gregory, Geoffrey, Bullock, James, Javey, Ali, Kushima, Akihiro, & Davis, Kristopher O. Thermal Stability of Hole-Selective Tungsten Oxide: In Situ Transmission Electron Microscopy Study. United Kingdom. doi:10.1038/s41598-018-31053-w.
Ali, Haider, Koul, Supriya, Gregory, Geoffrey, Bullock, James, Javey, Ali, Kushima, Akihiro, and Davis, Kristopher O. Thu . "Thermal Stability of Hole-Selective Tungsten Oxide: In Situ Transmission Electron Microscopy Study". United Kingdom. doi:10.1038/s41598-018-31053-w.
@article{osti_1464976,
title = {Thermal Stability of Hole-Selective Tungsten Oxide: In Situ Transmission Electron Microscopy Study},
author = {Ali, Haider and Koul, Supriya and Gregory, Geoffrey and Bullock, James and Javey, Ali and Kushima, Akihiro and Davis, Kristopher O.},
abstractNote = {In this study, the thermal stability of a contact structure featuring hole-selective tungsten oxide (WOx) and aluminum deposited onto p-type crystalline silicon (c-Si/WOx/Al) was investigated using a combination of transmission line measurements (TLM) and in situ transmission electron microscopy (TEM) studies. The TEM images provide insight into why the charge carrier transport and recombination characteristics change as a function of temperature, particularly as the samples are annealed at temperatures above 500 °C. In the as-deposited state, a ≈ 2 nm silicon oxide (SiOx) interlayer forms at the c-Si/WOx interface and a ≈ 2–3 nm aluminum oxide (AlOx) interlayer at the WOx/Al interface. When annealing above 500 °C, Al diffusion begins, and above 600 °C complete intermixing of the SiOx, WOx, AlOx and Al layers occurs. This results in a large drop in the contact resistivity, but is the likely reason surface recombination increases at these high temperatures, since a c-Si/Al contact is basically being formed. This work provides some fundamental insight that can help in the development of WOx films as hole-selective rear contacts for p-type solar cells. Furthermore, this study demonstrates that in situ TEM can provide valuable information about thermal stability of transition metal oxides functioning as carrier-selective contacts in silicon solar cells.},
doi = {10.1038/s41598-018-31053-w},
journal = {Scientific Reports},
number = 1,
volume = 8,
place = {United Kingdom},
year = {2018},
month = {8}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1038/s41598-018-31053-w

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