Transmission Electron Microscopy Studies of Electron-Selective Titanium Oxide Contacts in Silicon Solar Cells

Haider Ali; Xinbo Yang; Klaus Weber; Winston V Schoenfeld; Kristopher O Davis

doi:10.1017/S1431927617012417

Transmission Electron Microscopy Studies of Electron-Selective Titanium Oxide Contacts in Silicon Solar Cells

Microsc Microanal. 2017 Oct;23(5):900-904. doi: 10.1017/S1431927617012417. Epub 2017 Aug 15.

Authors

Haider Ali^{1

2

3}, Xinbo Yang^{4

5}, Klaus Weber⁴, Winston V Schoenfeld^{1

2

3

6}, Kristopher O Davis^{2

3}

Affiliations

¹ Department of Materials Science and Engineering, University of Central Florida, 12760 Pegasus Drive, Engineering I, Suite 207, Orlando, FL 32816, USA.
² Florida Solar Energy Center, University of Central Florida, 1679 Clearlake Rd, Cocoa, FL 32922, USA.
³ c-Si Division, U.S. Photovoltaic Manufacturing Consortium, 12354 Research Parkway, Suite 210, Orlando, FL 32826, USA.
⁴ Research School of Engineering, Engineering Building 32, North Road, The Australian National University, ACT 0200, North Rd, Acton ACT 2601, Canberra, Australia.
⁵ KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia.
⁶ CREOL, The College of Optics & Photonics, University of Central Florida, 4304 Scorpius St, Orlando, FL 32816, USA.

PMID: 28809136
DOI: 10.1017/S1431927617012417

Abstract

In this study, the cross-section of electron-selective titanium oxide (TiO2) contacts for n-type crystalline silicon solar cells were investigated by transmission electron microscopy. It was revealed that the excellent cell efficiency of 21.6% obtained on n-type cells, featuring SiO2/TiO2/Al rear contacts and after forming gas annealing (FGA) at 350°C, is due to strong surface passivation of SiO2/TiO2 stack as well as low contact resistivity at the Si/SiO2/TiO2 heterojunction. This can be attributed to the transformation of amorphous TiO2 to a conducting TiO2-x phase. Conversely, the low efficiency (9.8%) obtained on cells featuring an a-Si:H/TiO2/Al rear contact is due to severe degradation of passivation of the a-Si:H upon FGA.

Keywords: TiO2; crystalline silicon; electron-selective contact; solar cell.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.
Research Support, Non-U.S. Gov't