Project Title: Crystalline silicon surface passivation
Project Leader: Zahidur R Chowdhury
Supervisor: Prof. Nazir P. Kherani
Other Member(s): Zhou Lin [summer Student], Kevin Cho [summer student], Heidi Potts [visiting graduate student], David Barchet [graduate student]
My role: Design of experiment, passivation quality measurement, analysis of the passivation quality, training team members, trouble shooting, report writing.
Tools used: Oxford PlasmaLab 100 PECVD System / SOPRA Spectroscopic Ellipsometer / Sinton Silicon Lifetime Tester / Semilab’s µ-PCD lifetime tester / X-ray Photo-electron Spectroscopy (XPS)/ MATLAB / LATEX / Microsoft Office / Origin
Summary
- High quality surface passivation of crystalline silicon has been attained using facile native oxide and plasma enhanced chemical vapour deposition SiNx. Using systematic measurements of excess carrier density dependent minority carrier lifetime, it is observed that the inferred interface defect density decreases with increasing native oxide thickness while the interface charge density remains unchanged with thickness, which ranges from 0.2Å to 10Å. A surface recombination velocity of 8 cm/s is attained corresponding to a native oxide layer thickness of 10Å . Similar chemically grown oxide layer followed by SiNx deposition is shown to yield comparable passivation, indicating practical viability of the passivation scheme.
- Figure: (left) Spatial profile of the lifetime measured using µ-PCD tool (right) passivation quality comparison of the proposed scheme with highest reported quality of other schemes.
Publication(s)
N P Kherani and Z R Chowdhury, “Passivation of Silicon Surfaces Using Intermediate Ultra-thin Silicon Oxide and Outer Silicon-based Dielectric Layer”, US Patent Application No. 13/829,206, Priority date: 11 May 2012. link
Zahidur R. Chowdhury, Kevin Cho and Nazir P Kherani, “High-quality surface passivation of silicon using native oxide and silicon nitride layers”, Applied Physics Letters, vol. 101(2), pp. 021601, 2012. [ Impact factor 3.8 ] view / link
Zahidur R. Chowdhury and Nazir P. Kherani, “Facile grown oxide based passivation for silicon heterojunction PV cells”, presented in International Conference on Amorphous and Nanocyrstalline Semiconductor (ICANS), Toronto, Canada, 2013. view / link
[ Invited ] Nazir P. Kherani and Zahidur R. Chowdhury, “Facile native oxide based passivation of silicon: an unconventional approach”, presented in Materials Science & Technology 2013, Montreal, 2013. view / link
[ Invited ] Nazir P. Kherani and Zahidur R. Chowdhury, “Nanometer thick native oxide based passivation of silicon for high efficiency photovoltaics”, presented in International Nanoelectronics Conference (INEC), Singapore, 2013. view / link