Silicon Carbide MOSFETs

Details of project plan including key milestones - UMOS technology consists of a vertical channel region, adjacent to the usual lateral plane. This rotation will have an impact on the arrangement of atoms at the interface since the structure of 4H-SiC will be off-orientated. A slightly higher mobility should be achieved in this device due to aspects provided by this different orientation.

The first milestone will be fabricating UMOS technology with interface trap density values of a magnitude equal to or lower than that seen in SiC oxide layers.
A UMOS capacitor will be designed and fabricated with analysis of interface trap density, mobility and hysteresis.

Upon success of this milestone, the second milestone will be fabrication of a single UMOS power transistor cell:
A UMOSFET will be designed and fabricated. A mask will be designed for this and a DMOS transistor to be on a single wafer. The two technologies characteristics can be directly compared. The UMOS device will be characterised.

However, if in the first phase, the UMOS technology shows little promise in its current carrying capability, other team members will be working on design of the DMOSFET and I can join them with the task of characterisation of this device.

The third milestone will be carrying out reliability analysis:
Assessing the reliability of both power MOSFET devices, addressing potential reliability problems by examining failure probability when the device is operated under certain parameters (such as temperature and current) for a period of time.

Summary of the proposed project - Silicon Carbide is a wide band-gap semiconductor with exceptional electrical and other material properties for power electronics applications. But it has very poor MOS current carrying capability and I-V hysteresis. We have shown recently that major (10x) performance improvements can be achieved by nm scale engineering of the gate stack (DOI: 10.1109/TED.2019.2901310). This PhD project will build on this new approach and look at both power MOSFETs I-V performance and reliability. The research will include device fabrication, characterisation and analysis.

This CDT will produce power electronics specialists with industrial experience, and will equip them with key skills that are essential to meet the future power electronics challenges. They will be highly employable due to their training being embedded in industrial challenges with the potential to become future leaders through parallel entrepreneurial and business acumen training. As such, they will drive the UK forward in electric propulsion development and manufacturing. They will become ambassadors for cross-disciplinary thinking in electric propulsion and mentors to their colleagues. With its strong industrial partnership, this CDT is ideally placed to produce high impact research papers, patents and spin-outs, with support from the University's dedicated business development teams. All of this will contribute to the 10% year upon year growth of the power electronics sector in the UK, creating more jobs and added value to the UK economy.

Alongside the clear benefits to the economy this CDT will sustain and enhance the UK as a hub of expertise in this rapidly increasing area. UK R&D is set to shift dramatically to electrical technologies due to, amongst other reasons, the target to ban petrol/ diesel propulsion by 2040. Whilst the increase in R&D is welcome this target will be unsustainable without the right people to support the development of alternative technologies. This CDT will directly answer this skills shortage enabling the UK to not only meet these targets but lead the way internationally in the propulsion revolution.

Industry and policy stakeholders will benefit through-
a) Providing challenges for the students to work through

b) Knowledge exchange with the students and the academics

c) New lines of investigation/ revenue/ process improvement

d) Two way access to skills/ equipment and training

e) A skilled, challenge focused workforce


Society will benefit through-
a) Propulsion systems that are more efficient and require therefore less energy reducing cost of travel

b) Engineers with new skillsets working more cost-effective and more productive

c) Skilled workforce who are mindful considering the environmental and ethical impact

d) Graduates that understand equality, diversity and inclusion


Environment will benefit through-
a) Emission free cars powered by clean renewable energy increasing air quality and reducing global warming

b) Highly efficient planes reducing the amount of oil and therefore oil explorations in ecological sensitive areas such as the arctic can be slowed down, allowing sufficient time for the development of new alternative environmental friendly fuels.

c) Significant noise reduction leading to quiet cities and airports