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Prof. Lisa Porter
September 21, 2018 @ 11:00 am - 12:00 pm
Title: Research and Development of Gallium-Oxide Semiconductors for Ultra-High Efficiency Electronics
Affiliation: Materials Science and Engineering, CMU, Pittsburgh, PA
ABSTRACT: Gallium oxide (Ga2O3) is an ultra-wide bandgap semiconductor that is expected to push the operating boundaries for a variety of electronic and optoelectronic applications. Its extreme properties and recent availability as single-crystal substrates provide a platform to transform future device technologies associated with high-power/high-frequency/high-temperature/radiation-hard electronics. For example, power electronics are needed for efficient electrical switching within the electrical grid, for power supplies in hybrid electric vehicles, and for power conversion units that integrate renewable energy systems into the grid. In each of these applications, the power semiconductor device is the critical component that determines the energy conversion efficiency, in addition to the size and cost of the system. Although silicon devices have been traditionally used for power electronics, wide bandgap semiconductors, which can withstand higher electric fields with less material and reduced energy loss, are taking hold in an increasing number of applications. As an example, Toyota recently began trials of a new hybrid system using power electronics based on the wide bandgap semiconductor SiC and claims that power electronic devices based on SiC could increase fuel efficiency of hybrid vehicles by 10%. However, the substrates of SiC and GaN (another WBG semiconductor) are produced from highly energy-intensive vapor-phase processes and still very expensive, slowing their wide-scale adoption. A promising alternative to SiC and GaN is gallium oxide, Ga2O3, which has an even larger bandgap than that of SiC or GaN; moreover, b-Ga2O3 bulk single crystals can be grown using inexpensive melt-growth methods, and have recently become commercially available in 2-in diameter wafers. The prospect of a ‘new’ wide bandgap semiconductor having both superior properties for many electronic and optoelectronic devices as well as commercially-available substrates is a novelty not seen in the wide bandgap semiconductor field for at least two decades. In this presentation I will give an overview of the properties and R&D status of Ga2O3 for electronic devices. Along the way I will include examples from our research on the development of ohmic and Schottky contacts and the growth of epitaxial layers of different polymorphs (a, b, and e) of Ga2O3.
BIOGRPAHY: Lisa Porter is Professor of Materials Science & Engineering at Carnegie Mellon University in Pittsburgh, Pennsylvania and is an alumna of N.C. State, where she received her Ph.D in 1994. Her research, which initially focused on metal contacts and oxide-SiC interfaces for high-temperature and high-power device applications, broadened to include fabrication, processing, and characterization of a wide range of electronic materials, with recent focus on gallium oxide as a promising new wide bandgap semiconductor. In 2011 she co-founded SenSevere LLC, a Carnegie Mellon spin-off to commercialize semiconductor-based chemical sensors for severe environments. Lisa holds leadership positions in a number of professional organizations. She is President of the American Vacuum Society (AVS), an international research society pertaining to the Science & Technology of Materials, Interfaces, and Processing. Outside of AVS she served two terms on the User Executive Committee for the Environmental Molecular Sciences Laboratory (EMSL) at the Pacific Northwest National Laboratory (PNNL), serves as Secretary of the Electronic Materials Conference, and is an ABET Program Evaluator. Some of her awards include an NSF Career Award, a Swedish Research Foundation Professor Award, Women in Materials Award, and CMU’s Philbrook Prize in Engineering. Her work has been recognized through many invited presentations and will be featured in her Plenary Talk at the Taiwan Association for Coatings and Technology Annual Meeting in Taipei, Taiwan in October.