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

Ali, Haider; Koul, Supriya; Gregory, Geoffrey; Bullock, James; Javey, Ali; Kushima, Akihiro; Davis, Kristopher O.

doi:10.1038/s41598-018-31053-w

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

Journal Article · Thu Aug 23 00:00:00 EDT 2018 · Scientific Reports

DOI:https://doi.org/10.1038/s41598-018-31053-w· OSTI ID:1464976

Ali, Haider; Koul, Supriya;

;

; Javey, Ali; Kushima, Akihiro;

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 about thermal stability of transition metal oxides functioning as carrier-selective contacts in silicon solar cells.

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Research Organization:: Univ. of Central Florida, Orlando, FL (United States); Univ. of California, Oakland, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office

Grant/Contract Number:: EE0007533; AC02- 05CH11231; AC02-05CH11231

OSTI ID:: 1464976

Alternate ID(s):: OSTI ID: 1546082; OSTI ID: 1638981

Journal Information:: Scientific Reports, Journal Name: Scientific Reports Vol. 8 Journal Issue: 1; ISSN 2045-2322

Publisher:: Nature Publishing GroupCopyright Statement

Country of Publication:: United Kingdom

Language:: English

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Cited by: 18 works

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