Nature of defects in silicon for very high efficiency solar cells
Recent studies have shown that defects limiting the lifetime of high-quality n-type silicon were unlikely to be related to metals or oxygen precipitates. These promising results were demonstrated using room-temperature passivation or photoluminescence lifetime imaging. In fact, these two techniques open a whole new range of possibilities in the study of very dilute defects in silicon which a student could capitalize-on. Applications include imaging of defects in as-grown ingots and determination of defect reaction with low activation energy.
Rougieux, F.E.et al. IEEE Journal of Photovoltaics, 2015, 5, 495-498
Zheng, P., Rougieux, F.E.et al. IEEE Journal of Photovoltaics, 2015, 5, 183-188
Grant, N.E., Rougieux, F.E. et al. Journal of Applied Physics, 2015, 117 (5), 055711
Rougieux, F.E. et al. physica status solidi (RRL)-Rapid Research Letters, 2013, 7 (9), 616-618
Development of new characterization techniques
The mobility sum is a vital information for the understanding and modelization of silicon solar cells. We invented a new simple and contactless method allowing the measurement of the electron and hole mobility sum in silicon as a function of both carrier injection and temperature. This rapid and easily implementable technique is currently being used by our collaborators in other research institutes. Recently commonly accepted mobility models have been challenged in compensated silicon. These techniques and new ones that we are developing will be of fundamental importance to develop a new mobility model.
Rougieux, F. E. et al. IEEE Journal of Photovoltaics, 2011, 2, 1 -6
Hameiri, Z., Rougieux, F.E. et al. Applied Physics Letters, 2014, 104 (7), 073506
There is also scope to develop advance techniques to measure the spatial distribution of vacancies and oxygen in silicon.
Lim, S.Y., Rougieux, F.E. et al. Applied Physics Letters, 2013, 103 (9), 092105
As well has developing room temperature passivation techniques for photluminescence imaging similar to light-induced hydrofluoric passivation techniques
Grant, N.E., McIntosh, K.R., Tan, J., Rougieux, F.E. et al, Proceedings of the 28th European Photovoltaic Solar Energy Conference 2013
Understanding and mitigating the boron-oxygen defect in solar grade silicon
The boron-oxygen defect is one of the most detrimental defects for solar cells and has been well studied in p-type silicon. However its impact in compensated solar-grade silicon is still not well understood and more work need to be done to passivate this defect efficiently. There has been many contribution that challenged the commonly accepted structure of this well-known defect, leading to the development of a new defect model. The positive conclusions of these studies in regards to the quality of compensated p-type silicon have led to a regain of interest for this material.
Macdonald, D., Rougieux, F. et al. Journal of Applied Physics, 2009, 105, 093704
Lim, B., Rougieux, F. et al. Journal of Applied Physics, 2010, 108, 103722
Forster, M., Fourmond, E., Rougieux, F. E. et al. Applied Physics Letters, AIP, 2012, 100, 042110
Compensated n-type silicon may not be suitable for high efficiency silicon solar cells unless the boron-oxygen defect is mitigated. New defect-engineering processes or hydrogenation need to be designed to tackle this defect.
Rougieux, F. E. et al. Journal of Applied Physics, AIP, 2011, 110, 063708
Rougieux, F. E. et al. IEEE Journal of Photovoltaics, 2011, 1, 54 -58