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Peter Wilshaw

Professor Peter R Wilshaw
Professor of Materials

Department of Materials
University of Oxford
16 Parks Road
Oxford OX1 3PH
UK

Tel: +44 1865 273736 (Room 276.50.15)
Tel: +44 1865 273777 (reception)
Fax: +44 1865 273783

Semiconductor and Silicon Photovoltaics Group

Summary of Interests

My interests are those of the Semiconductor and Silicon Photovoltaics group. They are described in more detail at http://semiconductor.materials.ox.ac.uk/ 

In brief the group researches the properties and processing of semiconductors particularly silicon and particularly with reference to the production of improved solar cells. The research comprises four main areas.

 

  • The use of permanent charges introduced into dielectrics for surface passivation and application to novel cell geometries, passivated contacts etc.
  • The development of shielded hydrogen passivation for improved surface and bulk passivation.
  • Understanding and improving gettering processes which includes saw damage gettering, developing novel high temperature gettering processes and atom by atom analysis of electrically active defects (as characterised by electron beam induced current, EBIC) using atom probe tomography.
  • The development of a new vapour phase texturing technique for all silicon types including diamond wire sawn HP-multi.

 

 

 

Research Publications

Potassium ions in SiO2: electrets for silicon surface passivation

Ruy Sebastian Bonilla and Peter Wilshaw

Journal of Physics D: Applied Physics. 2017 doi.org/10.1088/1361-6463/aa9b1b

 

Instability of Increased Contact Resistance in Silicon Solar Cells Following Post-Firing Thermal Processes

Catherine Chan, Phillip Hamer, Gabrielle Bourret-Sicotte, Ran Chen, Alison Ciesla, Brett Hallam, David Payne, Ruy S. Bonilla and Stuart Wenham

RRL Solar, 2017, DOI: 10.1002/solr.201700129

 

Effective Antireflection and Surface Passivation of Silicon Using a SiO2/a-TiOx Film Stack

Ruy Sebastian Bonilla ; Kristopher O. Davis ; Eric J. Schneller ; Winston V. Schoenfeld ; Peter R. Wilshaw

IEEE Journal of Photovoltaics, 2017

 

Shielded hydrogen passivation – a novel method for introducing hydrogen into silicon

Gabrielle Bourret-Sicotte, Phillip Hamer, Ruy S. Bonilla, Katherine Collett, Peter R. 

Energy Procedia, Volume 124, September 2017, Pages 267-274

 

Method of Extracting Solar Cell Parameters From Derivatives of Dark I–V Curves

Brett J. Hallam, Phill G. Hamer, Ruy S. Bonilla, Stuart R. Wenham, and Peter R. Wilshaw

IEEE Journal of Photovoltaics, Vol 7, Issue 5, pp 1304 - 1312, 2017

 

Specimen preparation methods for elemental characterisation of grain boundaries and isolated dislocations in multicrystalline silicon using atom probe tomography

C. Lotharukpong, D. Tweddle, T.L. Martin, M. Wu, C.R.M. Grovenor, M.P. Moody, P.R. Wilshaw

Materials Characterisation, Volume 131, September 2017, Pages 472-479

 

An enhanced alneal process to produce SRV < 1 cm/s in 1 Ω cm n-type Si

Katherine A. Collett, Ruy S. Bonilla, Phillip Hamer, Gabrielle Bourret-Sicotte, Richard Lobo, Teng Kho, Peter R. Wilshaw

Solar Energy Materials and Solar Cells, 2017, DOI j.solmat.2017.06.022

 

Shielded hydrogen passivation − A potential in-line passivation process

Gabrielle Bourret-Sicotte, Phillip Hamer, Ruy. S. Bonilla, Katherine Collett, Alison Ciesla, Jack Colwell and Peter R Wilshaw

Phys. Status Solidi A (2017) 10.1002/pssa.201700383

 

Saw Damage Gettering for industrially relevant mc-Si feedstock

Eleanor C. Shaw, Phillip Hamer, Katherine A. Collett, Gabrielle Bourrett-Sicotte, Ruy S. Bonilla and Peter R. Wilshaw

Phys. Status Solidi A (2017) 10.1002/pssa.201700373

 

Dielectric surface passivation for silicon solar cells: A review

Ruy S. Bonilla, Bram Hoex, Phillip Hamer and Peter R. Wilshaw

Phys. Status Solidi A (2017) DOI: 10.1002/pssa.201700293

 

On the c-Si/SiO2 interface recombination parameters from photo-conductance decay measurements

Ruy S. Bonilla and Peter R. Wilshaw

Journal of Applied Physics 121, 135301 (2017)

 

Long term stability of c-Si surface passivation using corona charged SiO2

Ruy S. Bonilla Christian Reichel Martin Hermle Phillip Hamer Peter R. Wilshaw

Applied Surface Science, 2017, DOI: 10.1016/j.apsusc.2017.03.204

 

A novel source of atomic hydrogen for passivation of defects in silicon

Phillip Hamer, Gabrielle Bourret-Sicotte, George Martins, Alison Wenham, Ruy S. Bonilla and Peter Wilshaw

Phys. Status Solidi RRL,  (2017) DOI: 10.1002/pssr.201600448

 

Extremely low surface recombination in 1 Ω cm n-type monocrystalline silicon

Ruy S. Bonilla, Christian Reichel, Martin Hermle, Peter R. Wilshaw

Phys. Status Solidi RRL, 1, 1600307 (2017)

 

Passivation of all-angle black surfaces for silicon solar cells

T Rahman, RS Bonilla, A Nawabjan, PR Wilshaw, SA Boden

Solar Energy Materials and Solar Cells 160 (2017) 444–453

 

Corona Field Effect Surface Passivation of n-type IBC Cells

RS Bonilla, C Reichel, M Hermle, PR Wilshaw

Energy Procedia 92, 336-340, 2016

 

Corona Charge in SiO 2: Kinetics and Surface Passivation for High Efficiency Silicon Solar Cells

 

RS Bonilla, N Jennison, D Clayton-Warwick, KA Collett, L Rands, ...

Energy Procedia 92, 326-335, 2016

 

Stable, Extrinsic, Field Effect Passivation for Back Contact Silicon Solar Cells

RS Bonilla, K Collett, L Rands, G Martins, R Lobo, PR Wilshaw

Solid State Phenomena 242, 67-72, 2015

 

Minority Carrier Lifetime Improvement of Multicrystalline Silicon Using Combined Saw Damage Gettering and Emitter Formation

G Martins, RS Bonilla, T Burton, P MacDonald, PR Wilshaw

Solid State Phenomena 242, 126-132, 2015

 

Extrinsic Passivation of Silicon Surfaces for Solar Cells. 

Ruy S. Bonilla , Christian Reichel, Martin Hermle, George Martins, Peter R. Wilshaw

Energy Procedia. Volume 77, August 2015, Pages 774–778

 

Charge transport in nanocrystalline SiC with and without embedded Si nanocrystals

M. Schnabel, M. Canino, S. Kühnhold-Pospischil, J. López-Vidrier, T. Klugermann, C. Weiss, L. López-Conesa, M. Zschintzsch-Dias, C. Summonte, P. Löper, S. Janz, and P. R. Wilshaw

Phys. Rev. B 91, 195317 (2015)

Very low surface recombination velocity in n-type c-Si using extrinsic field effect passivation

Ruy S. Bonilla, Frederick Woodcock and Peter R. Wilshaw

J. Appl. Phys. 116, 054102 (2014)

Nanocrystalline SiC formed by annealing of a-SiC:H on Si substrates: A study of dopant interdiffusion 

Manuel Schnabel, Charlotte Weiss, Philipp Löper, Mariaconcetta Canino, Caterina Summonte, Peter R. Wilshaw and Stefan Janz.

J. Appl. Phys. 116, 024315 (2014)

A technique for field effect surface passivation for silicon solar cells

Ruy S. Bonilla and Peter R. Wilshaw

Appl. Phys. Lett. 104, 232903 (2014)

Boron Diffusion in Nanocrystalline 3C-SiC

M. Schnabel, A. Siddique, M. Canino, C. Weiss, T. Rachow, P. Löper, C. Summonte, S. Mirabella, S. Janz, P. Wilshaw.

Applied Physics Letters 104, 213108 (2014)

On the location and stability of charge in SiO2/SiNx dielectric double layers used for silicon surface passivation

Ruy S. Bonilla, Christian Reichel, Martin Hermle and Peter R. Wilshaw

J. Appl. Phys. 115, 144105, 2014

Controlled field effect surface passivation of crystalline n-type silicon and its application to back-contact silicon solar cells

R. S. Bonilla, C. Reichel, M. Hermle, S. Senkader, and P. Wilshaw.

In 2014 IEEE 40th Photovoltaic Specialist Conference (PVSC), 2014, pp. 0571�0576.

Electrical and Optical Characterisation of Silicon Nanocrystals Embedded in SiC

M. Schnabel, P. Löper, M. Canino, S.A. Dyakov, M. Allegrezza, M. Bellettato, J. López-Vidrier, S. Hernández, C. Summonte, B. 

Garrido, P.R. Wilshaw, S. Janz, Solid State Phenomena, 205-6 (2014) 480-485

Electric Field Effect Surface Passivation for Silicon Solar Cells

Ruy S. Bonilla, Christian Reichel, Martin Hermle, Peter R. Wilshaw

Solid State Phenomena, Volume 205-206, 2014, Pages 346-351

Thermal oxidation and encapsulation of silicon–carbon nanolayers

Manuel Schnabel, Philipp Löper, Sebastian Gutsch, Peter R. Wilshaw, Stefan Janz

Thin Solid Films, 527 (2013) 193-199

Stable Field Effect Surface Passivation of n-type Cz Silicon

Ruy S. Bonilla, Peter R. Wilshaw

Energy Procedia, Volume 38, 2013, Pages 816–822

Preliminary investigation of flash sintering of SiC

E. Zapata-Solvas, S. Bonilla, P. R. Wilshaw, and R. I. Todd

J. Eur. Ceram. Soc., vol. 33, no. 11-12, Jun. 2013.

Chemical etching to dissolve dislocation cores in multicrystalline silicon

N.J. Gregori, J.D. Murphy, J.M. Sykes, P.R. Wilshaw

Physica B, Volume 407, Issue 15, 1 August 2012, Pages 2970–2973

Reduced microwave attenuation in coplanar waveguides using deep level impurity compensated Czochralski-silicon substrates

A. Abuelgasim, K. Mallik, P. Ashburn, D.M. Jordan, P.R. Wilshaw, R. J. Falster, C.H. de Groot

Semiconductor Science and Technology, 26 072001 (2011) 

The effect of impurity-induced lattice strain and Fermi level position on low temperature oxygen diffusion in silicon

Z. Zeng, J.D. Murphy, R.J. Falster, X. Ma, D. Yang, P.R. Wilshaw

Journal of Applied Physics, 109 063532 (2011) 

Determination of grain orientations in multi-crystalline silicon by reflectometry

Y. Wang, J.D. Murphy, P.R. Wilshaw

Journal of the Electrochemical Society, 157 H884 (2010) 

The development of semi-insulating silicon substrates for microwave devices

D. M. Jordan, R. H. Haslam, K. Mallik, R. J. Falster, P. R. Wilshaw

Journal of the Electrochemical Society, 157 H540 (2010) 

An investigation into fracture of multi-crystalline silicon

B.R. Mansfield, D.E.J. Armstrong, P.R. Wilshaw, J.D. Murphy

Solid State Phenomena, 156-158 55 (2010) 

Semi-insulating silicon for microwave devices

D.M. Jordan, K. Mallik, R.J. Falster, P.R. Wilshaw

Solid State Phenomena, 156-158 101 (2010) 

A novel nano-porous alumina biomaterial with potential for loading with bioactive materials

A.R. Walpole, Z. Xia, C.W. Wilson, J.T. Triffitt, P.R. Wilshaw

Journal of Biomedical Materials Research - Part A, 90 46 (2009) 

Secondary electron emission contrast of quantum wells in GaAs p-i-n junctions

E. Grunbaum, Z. Barkay, Y. Shapira, K.W.J. Barnham, D.B. Bushnell, N.J. Ekins-Daukes, M. Mazzer, P. Wilshaw 

Microscopy and Microanalysis, 15 125 (2009) 

Cathodoluminescence assessment of annealed silicon and a novel technique for estimating minority carrier lifetime in silicon

K.J. Fraser, R.J. Falster, P.R. Wilshaw

Materials Science and Engineering B, 159-160 194 (2009) 

Nitrogen in silicon: diffusion at 500 to 700°C and interaction with dislocations

C.R. Alpass, J.D. Murphy, R.J. Falster, P.R. Wilshaw

Materials Science and Engineering B, 159-160 95 (2009) 

Measurements of dislocation locking by near-surface ion-implanted nitrogen in Czochralski silicon

C.R. Alpass, A. Jain, J.D. Murphy, P.R. Wilshaw

Journal of the Electrochemical Society, 156 H669 (2009) 

Nitrogen diffusion and interaction with dislocations in single-crystal silicon

C.R. Alpass, J.D. Murphy, R.J. Falster, P.R. Wilshaw

Journal of Applied Physics, 105 013519 (2009) 

The development of semi-insulating silicon substrates for microwave devices

D.M. Jordan, R.H. Haslam, K. Mallik, P.R. Wilshaw

ECS Transactions, 16 41 (2008) 

Measurements of dislocation locking by near-surface ion-implanted nitrogen in Czochralski silicon

C.R. Alpass, J.D. Murphy, A. Jain, P.R. Wilshaw

ECS Transactions, 16 249 (2008) 

Cathodoluminescence assessment of low temperature gettering in silicon and a novel technique for estimating bulk minority carrier lifetime in silicon

K.J. Fraser, R.J. Falster, P.R. Wilshaw

ECS Transactions, 16 273 (2008) 

Counting electrons in transmission electron microscopes

G. Moldovan, X. Li, P. Wilshaw, A.I. Kirkland

Microscopy and Microanalysis, 14 912 (2008) 

Thin silicon strip devices for direct electron detection in transmission electron microscopy

G. Moldovan, X. Li, P. Wilshaw, A.I. Kirkland

Nuclear Instruments and Methods in Physics Research A, 591 134 (2008) 

Piezospectroscopic measurement of the stress field around an indentation crack tip in ruby using SEM cathodoluminescence

R.I. Todd, D. Stowe, S. Galloway, D. Barnes, P.R. Wilshaw

Journal of the European Ceramics Society, 28 2049 (2008) 

The role of dislocations in producing efficient near-bandgap luminescence from silicon

K. Fraser, D. Stowe, S. Galloway, S. Senkader, R. Falster, P. Wilshaw

Physica Status Solidi C, 4 2977 (2007) 

Out-diffusion of nitrogen from float-zone silicon measured by dislocation locking

C. R. Alpass, J.D. Murphy, A. Giannattasio, S. Senkader, R.J. Falster, P.R. Wilshaw

Physica Status Solidi A, 204 2256 (2007) 

Semi-insulating Czochralski-silicon for radio frequency applications

K. Mallik, C.H. de Groot, P. Ashburn, P.R. Wilshaw

Proceedings of the 36th European Solid-State Device Research Conference, 435 (2006) 

Enhanced oxygen diffusion in highly-doped p-type Czochralski silicon

J.D. Murphy, P.R. Wilshaw, B.C. Pygall, S. Senkader, R.J. Falster

Journal of Applied Physics, 100 103531 (2006) 

Nitrogen-doped silicon: mechanical, transport and electrical properties

J.D. Murphy, C.R. Alpass, A. Giannattasio, S. Senkader, D. Emiroglu, J.H. Evans-Freeman, R.J. Falster, P.R. Wilshaw

ECS Transactions, 3 239 (2006) 

Nitrogen in silicon: transport and mechanical properties

J.D. Murphy, C.R. Alpass, A. Giannattasio, S. Senkader, R.J. Falster, P.R. Wilshaw

Nuclear Instruments and Methods in Physics Research B, 253 113 (2006) 

Oxygen transport in Czochralski silicon investigated by dislocation locking experiments

J.D. Murphy, S. Senkader, R.J. Falster, P.R. Wilshaw

Materials Science and Engineering B, 134 176 (2006) 

Efficient room temperature near-band gap luminescence by gettering in ion implanted silicon

D.J. Stowe, K.J. Fraser, S.A. Galloway, S. Senkader, R.J. Falster, P.R. Wilshaw

Springer Proceedings in Physics, 107 35 (2005) 

The electric field and dopant distribution in p-i-n structures observed by ionisation potential (dopant contrast) microscopy in the HRSEM

E. Grunbaum, Z. Barkay, Y. Shapira, K. Barnham, D.B. Bushnell, N.J. Elkins-Daukes, M. Mazzer, P.R. Wilshaw

Springer Proceedings in Physics, 107 503 (2005) 

Transmission ion channeling analysis of isolated 60° misfit dislocations 

M.B.H. Breese, L. Huang, E.J. Teo, P.J.C. King, P.R. Wilshaw

Appl. Phys. Lett., 87 211907 (2005) 

The influence of nitrogen on dislocation locking in float-zone silicon

J.D. Murphy, A. Giannattasio, C.R. Alpass, S. Senkader, R.J. Falster, P.R. Wilshaw

Solid State Phenomena, 108-109 139 (2005) 

High resolution deep level transient spectroscopy applied to extended defects in silicon 

J.H. Evans-Freeman, D. Emiroglu, K.D. Vernon-Parry, J.D. Murphy, P.R. Wilshaw

Journal of Physics: Condensed Matter, 17 S2219 (2005) 

Oxygen and nitrogen transport in silicon investigated by dislocation locking experiments

A. Giannattasio, J.D. Murphy, S. Senkader, R.J. Falster, P.R. Wilshaw

Journal of the Electrochemical Society, 152 G460 (2005) 

Nitrogen transport in float-zone and Czochralski silicon investigated by dislocation locking experiments

J.D. Murphy, A. Giannattasio, S. Senkader, R.J. Falster, P.R. Wilshaw

Phys. Status Solidi A, 202 926 (2005) 

Impurity locking of dislocations in silicon

A. Giannattasio, J.D. Murphy, S. Senkader, R.J. Falster, P.R. Wilshaw

Proceedings of the 206th Meeting of The Electrochemical Society, High Purity Silicon VIII, Honolulu, USA (2004) 

Formation of highly adherent nano-porous alumina on Ti-based substrates: a novel bone implant coating

E.P. Briggs, A.R. Walpole, P.R. Wilshaw, M. Karlsson, E. Palsgard

J. Mater. Sci.: Mater. M., 15 1021 (2004) 

A room temperature cathodoluminescence study of dislocations in silicon

D.J. Stowe, S.A. Galloway, S. Senkader, K. Mallik, R.J. Falster, P.R. Wilshaw

Inst. Phys. Conf. Ser., 179 67 (2004) 

High-resolution scanning electron microscopy of dopants in p-i-n junctions with quantum wells

Z. Barkay, E. Grunbaum, Y. Shapira, P. Wilshaw, K. Barnham, B. Bushnell, N.J. Ekins-Daukes, M. Mazzer

Inst. Phys. Conf. Ser., 179 143 (2004) 

The role of prismatic dislocation loops in the generation of glide dislocations in Cz-silicon

A. Giannattasio, S. Senkader, R.J. Falster, P.R. Wilshaw

Comp. Mater. Sci., 30 131 (2004) 

Dislocation locking in silicon by oxygen and oxygen transport at low temperatures

S. Senkader, A. Giannattasio, R.J. Falster, P.R. Wilshaw

Solid State Phenomena, 95-96 43 (2004) 

Schottky diode back contacts for high frequency capacitance studies on semiconductors

K. Mallik, R.J. Falster, P.R. Wilshaw

Solid State Electronics, 48 231 (2004) 

Near-band gap luminescence at room temperature from dislocations in silicon

D.J. Stowe, S.A. Galloway, S. Senkader, K. Mallik, R.J. Falster, P.R. Wilshaw

Physica B, 340 710 (2003) 

Dislocation locking by nitrogen impurities in FZ-silicon

A. Giannattasio, S. Senkader, R.J. Falster, P.R. Wilshaw

Physica B, 340 996 (2003) 

Nano-porous alumina coatings for improved bone implant interfaces

A.R. Walpole, E.P. Briggs, M. Karlsson, E. Palsgard, P.R. Wilshaw

Materialwiss Werkst, 34 1064 (2003) 

The use of numerical simulation to predict the unlocking stress of dislocations in Cz-silicon wafers

A. Giannattasio, S. Senkader, S. Azam, R.J. Falster, P.R. Wilshaw

Microelectron. Eng., 70 125 (2003) 

'Semi-insulating' silicon using deep level impurity doping: problems and potential

K. Mallik, R.J. Falster, P.R. Wilshaw

Semicond. Sci. Tech., 18 517 (2003) 

Initial in vitro interaction of osteoblasts with nano-porous alumina

M. Karlsson, E. Palsgard, P.R. Wilshaw, L. Di Silvio

Biomaterials, 24 3039 (2003) 

Fabrication of nanocrystalline aluminium islands using double-surface anodization

S.E. Booth, C.D. Marsh, K. Mallik, V. Baranauskas, J.M. Sykes, P.R. Wilshaw

J. Vac. Sci. Technol. B, 21 316 (2003) 

Dislocation locking by oxygen in silicon: New insights to oxygen diffusion at low temperatures

S. Senkader, A. Giannattasio, R.J. Falster, P.R. Wilshaw

Elec. Soc. S., 2002 171 (2002) 

'Generation of dislocation glide loops in Czochralski silicon

A. Giannattasio, S. Senkader, R.J. Falster, P.R. Wilshaw

Journal of Physics: Condensed Matter, 14 12981 (2002) 

On the dislocation-oxygen interactions in Czochralski-grown Si: oxygen diffusion and binding at low temperatures

S. Senkader, A. Giannattasio, R.J. Falster, P.R. Wilshaw

Journal of Physics: Condensed Matter, 14 13141 (2002) 

Onset of slip in silicon containing oxide precipitates

K. Jurkschat, S. Senkader, P.R. Wilshaw, D. Gambaro, R.J. Falster

Journal of Applied Physics, 90 3219 (2001) 

Oxygen-dislocation interactions in silicon at temperatures below 700 degrees C: Dislocation locking and oxygen diffusion

S. Senkader, P.R. Wilshaw, R.J. Falster

Journal of Applied Physics, 89 4803 (2001) 

On the locking of dislocations by oxygen in silicon

S. Senkader, K. Jurkschat, D. Gambaro, R.J. Falster, P.R. Wilshaw

Philosophical Magazine A, 81 759 (2001) 

Large area gridded field emitter arrays using anodised aluminium

E.R. Holland, Y. Li, P. Abbott, P.R. Wilshaw

Displays, 21 99 (2000) 

Residual gas effects on the emission characteristics of silicon field emitter arrays

M.J. Gilkes, D. Nicolaescu, P.R. Wilshaw

J. Vac. Sci. Technol. B, 18 948 (2000) 

Synthesis of high density arrays of nanoscaled gridded field emitters based on anodic alumina

Y. Li, E.R. Holland, P.R. Wilshaw

J. Vac. Sci. Technol. B, 18 994 (2000) 

Mechanism for secondary electron dopant contrast in the SEM

C.P. Sealy, M.R. Castell, P.R. Wilshaw

J. Electron. Microsc., 49 311 (2000) 

A study of oxygen dislocation interactions in CZ-Si

S. Senkader, K. Jurkschat, P.R. Wilshaw, R.J. Falster

Materials Science and Engineering B, 73 111 (2000)

 

Projects Available

Exploiting extrinsic passivation on antireflection coatings for high efficiency silicon solar cells
Supervisors Prof PR Wilshaw and Dr S Bonilla

Semiconductor and Silicon PV group – Oxford Materials

In order to move to a low-carbon future, and avoid the worst effects of anthropogenic climate change, continuing reductions in the cost of renewable energy are required. The semiconductor group at Oxford Materials, in collaboration with international research partners at Fraunhofer ISE in Germany and the University of New South Wales in Australia as well as industry partners, is working to reduce the cost of photovoltaic cells. Graduate students would work as part of a dedicated group of researchers on state-of-the-art techniques for improving the performance of crystalline silicon solar cells, which account for over 90% of all currently manufactured solar cells.

Silicon solar cells capture solar energy when light is absorbed near the cell’s surface. The surface of the cell represents a major material defect where loss of charge carriers may occur. The reduction of charge loss at the surface, termed passivation, is hence a critical feature requiring improvement. For solar energy to be cost competitive with other technologies, manufacturing costs of solar cells must be brought down while maintaining device performance. This project aims to explore a new generation of cost effective dielectric coatings that provide optimal passivation using the technologies proposed and patented by the group, as well as improving the optical qualities over current industrial films. The student performing the work will be involved in deposition of dielectrics using semiconductor facilities and characterisation of their properties using electronic techniques. These films will then be extrinsically treated to exploit their passivation characteristics.

 

Also see homepages: Peter Wilshaw

Advanced Gettering of Multicrystalline Silicon for Commercial Solar Cells
Prof PR Wilshaw and Dr S Bonilla

Semiconductor and Silicon PV group – Oxford Materials

In order to move to a low-carbon future, and avoid the worst effects of anthropogenic climate change, continuing reductions in the cost of renewable energy are required. The semiconductor group at Oxford Materials, in collaboration with international research partners at Fraunhofer ISE in Germany and the University of New South Wales in Australia as well as industry partners, is working to reduce the cost of photovoltaic cells. Graduate students would work as part of a dedicated group of researchers on state-of-the-art techniques for improving the performance of crystalline silicon solar cells, which account for over 90% of all currently manufactured solar cells.

Multicrystalline silicon is the most common wafer material for current solar cell production. As multicrystalline solar cell efficiencies increase, recombination due to impurities in the material becomes more and more important. These impurities may be present in the silicon feedstock, or introduced during casting of the multicrystalline ingot. The graduate student will work on developing advanced gettering techniques to remove these impurities from multicrystalline wafers, and on characterizing the improvement in device parameters that may be achieved. This will be done in collaboration with the atom probe tomography unit at Oxford Materials. These technologies may improve the performance of commercial multicrystalline silicon or enable the use of materials currently considered too contaminated for solar cell production. The student would work closely with a range of wafer suppliers, as well as international research partners to ensure the commercial relevance of the work.

 

Also see homepages: Peter Wilshaw

Hydrogen Passivation of Defect Engineered Silicon Solar Cells
Prof PR Wilshaw and Dr S Bonilla

Semiconductor and Silicon PV group – Oxford Materials

In order to move to a low-carbon future, and avoid the worst effects of anthropogenic climate change, continuing reductions in the cost of renewable energy are required. The semiconductor group at Oxford Materials, in collaboration with international research partners at Fraunhofer ISE in Germany and the University of New South Wales in Australia as well as industry partners, is working to reduce the cost of photovoltaic cells. Graduate students would work as part of a dedicated group of researchers on state-of-the-art techniques for improving the performance of crystalline silicon solar cells, which account for over 90% of all currently manufactured solar cells.

While multicrystalline silicon is currently the most cost effective material for the fabrication of solar cells, the high levels of defects and impurities present in this material limits the cell efficiencies that can be obtained. This is mostly through recombination of excited charge carriers at defect sites in the silicon bulk. The two most common approaches for reducing bulk recombination in crystalline silicon solar cells are defect engineering via gettering and hydrogen passivation. While both approaches are capable of reducing the recombination rate by more than an order of magnitude they are typically optimized separately. The graduate student would work in close collaboration with the world-leading hydrogen passivation group at the University of New South Wales to develop and apply hydrogen passivation techniques to defect engineered silicon. This would allow observation of how gettering techniques affect the ability of hydrogen to passivate the impurities remaining in the silicon and subsequently address optimization of both processing techniques.

Also see homepages: Peter Wilshaw

Stabilization of world record surface passivation for high efficiency silicon solar cells
Supervisors Prof PR Wilshaw and Dr S Bonilla

Semiconductor and Silicon PV group – Oxford Materials

In order to move to a low-carbon future, and avoid the worst effects of anthropogenic climate change, continuing reductions in the cost of renewable energy are required. The semiconductor group at Oxford Materials, in collaboration with international research partners at Fraunhofer ISE in Germany and the University of New South Wales in Australia as well as industry partners, is working to reduce the cost of photovoltaic cells. Graduate students would work as part of a dedicated group of researchers on state-of-the-art techniques for improving the performance of crystalline silicon solar cells, which account for over 90% of all currently manufactured solar cells.

Efficiency in the most advanced silicon solar cells is limited by recombination of photo-excited electron-hole pairs at surfaces and interfaces. Future generations of industrial high efficiency solar cells will require cost effective techniques for producing semiconductor/dielectric interfaces with very low rates of recombination. The process of creating these low recombination interfaces is known as surface passivation and its development is critical to the next generation solar cells. Existing work in the semiconductor group has produced record breaking surface passivation using charge extrinsically added to dielectric coatings. The problem, however, is that the passivation produced is not stable over a period of years as required for solar cells in the field. This project aims to develop new techniques that will stabilise the charge in dielectrics to produce superior and industrially relevant passivation of silicon surfaces.

The student performing the work will be involved in cleanroom processing and dielectric characterisation using electronic and optical techniques. They will have the opportunity to apply the passivation techniques to the most advanced silicon solar cell structures developed by research institutions around the world.

Also see homepages: Peter Wilshaw

Novel Photon Capture Methods for Multicrystalline Silicon
Prof PR Wilshaw and Dr S Bonilla

Semiconductor and Silicon PV group – Oxford Materials

In order to move to a low-carbon future, and avoid the worst effects of anthropogenic climate change, continuing reductions in the cost of renewable energy are required. The semiconductor group at Oxford Materials, in collaboration with international research partners at Fraunhofer ISE in Germany and the University of New South Wales in Australia as well as industry partners, is working to reduce the cost of photovoltaic cells. Graduate students would work as part of a dedicated group of researchers on state-of-the-art techniques for improving the performance of crystalline silicon solar cells, which account for over 90% of all currently manufactured solar cells.

Texturing of multicrystalline silicon wafers for solar cell production has been an ongoing concern for cell manufacturers. While anisotropic texturing of mono-crystalline silicon can reduce the weighted average reflection (WAR) of bare silicon to below 10%, most approaches on multicrystalline materials yield WAR’s in excess of 25%. Furthermore the traditional approach of using acidic etching solutions to preferentially attack defect sites is incompatible with new wafer sawing techniques. In this project the graduate student will develop novel texturing approaches for multicrystalline silicon. These techniques will be evaluated in collaboration with international research institutions and industrial partners including cell manufactures and wafer suppliers. If successful this technology will reduce the cost of solar electricity by realizing superior optical performance with a reduced cost of production.

Also see homepages: Peter Wilshaw

Also see a full listing of New projects available within the Department of Materials.