Computational discovery of new ultrawide-band-gap semiconductors for power electronics and deep-ultraviolet optoelectronics
Abstract: Atomistic calculations based on density functional theory and many-body perturbation theory provide predictive understanding of materials at the electronic level that complement experimental synthesis and characterization studies. Recent advances in modern software development and high-performance computing have enabled the high-throughput calculation of materials properties that can guide the discovery of new materials with targeted functionalities. Semiconductors in particular are a versatile class of functional materials with numerous commercial applications in electronic and optoelectronic devices. Recent interest has focused on ultrawide-band-gap semiconductors (i.e., semiconductors with gaps wider than the 3.5 eV gap of GaN) for applications in energy-efficient power electronics and deep-ultraviolet light emission for sterilization and water purification. However, existing ultrawide-band-gap semiconductors such as AlGaN alloys, Boron Nitride (BN), diamond, and Gallium Oxide (Ga2O3) face several challenges with regards to their doping, thermal conductivity, and efficiency of light generation.
In this talk I will present our recent results on the computational discovery of new ultrawide-gap semiconductors with superior properties compared to the state of the art. I will present rutile GeO2 as a promising alternative to nitrides and Ga2O3 for high-power electronic applications. I will discuss its superior electrical and thermal conductivity compared to Ga2O3 and the possibility of ambipolar doping. I will also discuss Boron-containing BAlGaN alloys and atomically thin GaN as alternative materials to AlGaN for efficient deep-ultraviolet light emission thanks to their easier growth on AlN substrates (and hence their lower threading dislocation density) and the emission of transverse-electric polarized light, which facilitates light extraction from polar devices. Our computational results can guide experimental efforts in the synthesis and characterization of these promising new semiconductors.
This work was supported by the Designing Materials to Revolutionize and Engineer our Future (DMREF) Program under Award No. 1534221, funded by the U.S. National Science Foundation. It used resources of the National Energy Research Scientific Computing Center, a DOE office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.