Researcher

Dr Udo Roemer

Keywords

Fields of Research (FoR)

Photodetectors, Optical Sensors and Solar Cells

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Biography

I am currently a DECRA fellow in the School of Photovoltaics and Renewable Energy Engineering, working on multi-junction (MJ) silicon (Si) solar cells for biomedical applications (see Research Activities).

 

I obtained my Diplom in Physics from the Justus-Liebig-Universität Gießen, Germany and worked towards my PhD at the Institute for Solar Energy Research Hameln (ISFH) in Hamelin, Germany, under supervision of Professor Niels Peter Harder,...view more

I am currently a DECRA fellow in the School of Photovoltaics and Renewable Energy Engineering, working on multi-junction (MJ) silicon (Si) solar cells for biomedical applications (see Research Activities).

 

I obtained my Diplom in Physics from the Justus-Liebig-Universität Gießen, Germany and worked towards my PhD at the Institute for Solar Energy Research Hameln (ISFH) in Hamelin, Germany, under supervision of Professor Niels Peter Harder, Professor Robby Peibst and Professor Tobias Wietler. My thesis research focussed on ion implanted, large area back-contact Si solar cells and on highly carrier selective poly-Si contacts for c-Si solar cells.

After receiving my PhD in electrical engineering from the Gottfried Wilhelm Leibniz Universität Hannover in Germany I moved to Sydney, Australia to work with Professor Alison Lennon at UNSW on inkjet and laser patterning processes for plated contacts for large area back-contacted Si solar cells and together with Professor Bram Hoex, on doped poly-Si passivating contacts. In 2018 I started my DFG (German Research Foundation) Research Fellowship at UNSW on inkjet printed doping of poly-Si contacts and in 2020 I joined the research Groups of A/Prof. Nicholas Ekins-Daukes and Dr. Stephen Bremner, where I worked on fabrication processes for III-V and III-V on Si solar cells.


My Grants

  • 2021-2023 ARC DECRA on "Nervous tissue stimulation using Multi-Junction Silicon Photodiodes", Funding: $442,408
  • 2019-2020 AUSIAPV Collaboration Grant on "Silicon Solar Cells with Silicon Carbide Passivated Contacts", Funding: $60,029
  • 2018-2019 DFG Research Stipend on "Doping of poly-Si contacts for high efficiency back junction back contact silicon solar cells using inkjet-printed doping sources", Funding: $145,580

My Qualifications

  • 2016: Dr.-Ing. (PhD) in electrical engineering from Gottfried Wilhelm Leibniz Universität Hannover in Germany on ""
  • 2010: Dipl.-Phys. (Masters Degree in Physics) from Justus-Liebig-Universität Gießen

My Awards

  • Solar World Junior Einstein Award 2016 for my PhD thesis
  • Silicon PV Award 2014 for one of the ten best ranked contributions to the Silicon PV conference 2014

My Research Activities

In my DECRA fellowship which started in mid 2021, I am aiming to fabricate multi-junction silicon photodiode arrays for use in brain machine interfaces like retinal implants.

Background: Two of the main causes of vision loss, retinitis pigmentosa and age-related macular degeneration, are caused by a degeneration of photoreceptors in the retina, while the remaining visual pathway stays intact. By placing electrodes in the retina, it is possible to electrically stimulate the remaining intact neural tissue and restoring vision.

The School of Photovoltaic & Renewable Energy Engineering within the UNSW Faculty of Engineering has been at the leading edge of solar cell development for over 30 years, reporting many world record solar cell efficiencies. In a collaboration with the UNSW Graduate School of Biomedical Engineering we are now aiming to develop solar cells that can stimulate nervous tissue upon illumination and to fabricate arrays of small solar cells as prototypes for wireless retinal prostheses and other light powered brain machine interfaces.

Schematic of the device
Left: Schematic of a multi-junction silicon solar cell. Right: Schematic of a multi solar cell array, indicating the local electric field generated upon illumination of one “pixel”. When placed in tissue, ions would flow along the indicated electric field lines and locally stimulate nerves.

Typically, electrodes in brain machine interfaces require voltages that are higher than the obtainable voltage of a single monocrystalline silicon solar cell. This project aims to stack multiple silicon solar cells on top of each other to overcome this limitation. One benefit of optically powered brain machine interfaces is that it will likely be easier to fabricate smaller devices with higher resolution. Instead of wires that need to be encapsulated, thin optical fibers could be used for powering the electrodes. An especially promising application would be a visual implant in the retina, since there not even fibers would be needed to power the device.

One major challenge for the project will be the fabrication of silicon tunnel-junctions that are needed at the interface between two cells and another challenge will be the microfabrication of an array consisting of many “pixels” of small multi-junction solar cells.


My Research Supervision


Supervision keywords


Areas of supervision

I am currently looking for undergrad and HDR students who are interested to work on novel semiconductor devices that have the potential to improve the quality of life for people suffering from blinding diseases and might result in a new type of optically powered brain machine interfaces (see Research Activities and https://www.qpvgroup.org/vacancies).

Ideal students for this project would have a background in electrical engineering, physics, material science, or similar, with some understanding of semiconductor physics and would be interested in silicon device fabrication and/or characterisation.

HDR candidates will be supported by a Research Stipend (according to the Australian Government Research Training Program (RTP) rate of AU$ 28,597 per year (2021 rate)), or a $10.000 top up per year for candidates that can get a government funded RTP scholarship.


Currently supervising

  • Mengdi Liu with her PhD thesis on "Metallisation for Advanced Solar Cells"
  • Abhinav Sanjay Sharma with his PhD thesis on "Investigating the use of remote valleys in PV devices"
  • Chukwuka Uzochukwu Madumelu with his PhD thesis on "Advanced hydrogenation on next-generation solar cells with passivated contacts"

Previously supervised PhD students

  • Qilin Ye on "Characterizing point contacting by localized dielectric breakdown and its use in Silicon Solar Cell Applications"
  • Chang-Yeh Lee on "Metal Oxide Thin Films for Silicon Solar Cells"
  • Tian Zhang on "Transition Metal Oxides and Their Application as Hole-Selective Contacts for Silicon Solar Cells"

My Teaching

I am supervising second to fourth year students in the Vertically-Integrated Project (VIP) “Mini Solar”, a project based course at UNSW, hold by Professor Alison Lennon, aiming to teach students to design and fabricate millimetre-sized PV devices that can provide a continuous source of power for Internet-of Things (IoT) sensors and medical implants by charging an on-chip Li-ion battery. As subproject leader (PV Device) I organise the design, fabrication and modelling of the miniature Si solar cell arrays.

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Location

School of Photovoltaic and Renewable Energy Engineering,
Tyree Energy Technologies Building (TETB) H6
Level1
Desk No - 123WS 8