Diamond and Ultra-Wide Bandgap Semiconductors for Power Electronics

There is growing recognition that upcoming challenges/opportunities such as the future electricity grid, beyond 5G communication, space-based installation and military communication and reconnaissance will be substantially advanced by ultra-wide bandgap semiconductors (UWBS). The UWBS, with a bandgap greater than 4 eV, and displaying high thermal conductivity and high carrier mobility most often discussed include diamond, AlN and AlGaN, Ga2O3 and (AlGa)2O3, and BN and BAlN. This talk will briefly summarize how the different ideal characteristics could favor specific materials groups for separate sets of applications. Basic materials properties and electrical characteristics are considered for p-i-n diodes including doping and transport properties. Here, the similarity of diamond to vacuum transport is described in terms of space charge limited current. Diamond is a bipolar material with p- and n-type doping with both high mobility band transport and hopping transport. Strategies to achieve desired electron and hole transport including conduction modulation are crucial for device configurations. The properties of dielectric-diamond interfaces are integral for communication applications. Oxides are usually considered for the dielectric layers, but recent research has considered fluorides, nitrides and multilayer dielectric structures. Here, band alignment, polarization doping, charge transfer doping, and interface states are of interest to achieve predicted performance. The impact of defects and impurities are now being identified in high performance diodes, and the electrical characteristics may help guide the materials development. Heterostructures and interface thermal properties will be crucial to integration of diamond with other UWBS materials. There is growing anticipation and even expectation that UWBG electronics will develop to play important roles in the future electricity grid and communications. For power electronics research co-design teams are being formed which span from the materials to grid design and all steps in between with a goal of effectively guiding the research at all levels - materials, devices, systems, architecture.<br/>Acknowledgement: Research supported by the US Department of Energy through the ULTRA Energy Frontier Research Center, NASA and the National Science Foundation.