EPSRC-SFI Aluminium-Rich Nitride Electronics (ARNE)

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Wide bandgap (WBG) semiconductors offer the potential to deliver electronic devices and systems with advanced power handling performance beyond that achievable in silicon. This stems from their intrinsic ability to operate at higher voltages, as attributed to their larger semiconductor bandgap. Although excellent progress has been made in the development of WBG technologies GaN and SiC, new and emerging materials with even larger bandgap (so called ultra-wide bandgap semiconductors) offer even greater potential performance gains. Maximising the high-power handling capability of such electronic components is essential to address many of the energy and environmental-related challenges that we currently face. For instance, advanced high-power solid-state systems will be required to enable smart power grids for future distribution of electricity and for efficient voltage conversion in electric vehicles. High power systems operating at high frequencies will also be required to meet the performance demands of future communication (e.g. beyond 6G mobile comms) and radar systems. AlGaN is an emerging ultra-wide bandgap (UWBG) material with the potential to deliver superior high-power handling at both low and millimetre wave frequencies than existing WBG semiconductor technologies, while crucially providing integration potential with the largely mature GaN material platform. In contrast to GaN, the introduction of aluminium to produce AlGaN increases the bandgap substantially, allowing for greatly increased breakdown field and even higher-voltage device operation for a higher Al composition. Doping of AlGaN, as required to convert the intrinsic material from an insulator into a semiconductor, is significantly more challenging than GaN however, particularly for higher Al compositions. Exploitation of polarisation-induced doping techniques similar to that used in GaN device technologies may however yield a route to realise the large potential of this material system for next generation high power electronic applications. In this work we will undertake a material investigation and evaluation study to assess and map crucial physical and electronic material properties for AlGaN epitaxial layers with 50% to 100% Al content (whereby the most benefit in terms of high-power device operation potential beyond GaN may be achieved), through a programme of material simulation, design, growth and characterisation. This initial material study will be coupled with and complemented by the development of Field Effect Transistor devices using the most promising of these material layers to demonstrate preliminary device performance potential. The outcomes of this study will be used to i) evaluate the potential of Al-rich AlGaN with a focus on high power RF device applications, ii) identify the technical challenges that need to be addressed to realise this potential for both high power and RF power applications iii) establish an ongoing research and exploitation strategy for UK and Irish academia and industry for Al-rich AlGaN-based technology.