Fundamentals of Doping and Defects in Ga2O3 for High Breakdown Field

2018 AFOSR MURI
Fundamentals of Doping and Defects in Ga2O3 for High Breakdown Field
PO: Dr. Ali Sayir
PI: Professor Michael Scarpulla, Departments of Materials Science and Engineering & Electrical and Computer Engineering, University of Utah

     β-Ga2O3 is an emerging ultra-wide band gap material with promise to enable next-generation high voltage power devices.  It is of interest to the DoD because of the fundamental importance of high voltage and power devices and systems.   
     A rigorous understanding of the interplay and control of doping, defects, interfaces and electronic transport under extreme environments is critical to unlock the full potential of β-Ga2O3. Our team of investigators is led by PI Michael A. Scarpulla at the University of Utah and includes Kelvin Lynn & Matthew McCluskey (Washington State University), Elif Ertekin (University of Illinois), Patrick Lenahan (Pennsylvania State University), Marco Bernardi (California Institute of Technology), James LeBeau (North Carolina State University), Sriram Krishnamoorthy & Berardi Sensale-Rodriguez (University of Utah).  
     The team brings together a unique collection of expertise in a wide range of topics that will be applied to investigate the fundamental materials properties β-Ga2O3 and unlock its potentials.  These include bulk oxide crystal growth, epitaxial growth, modification of semiconductor doping and defects in processing, ab-initio defect theory, atomic drift/diffusion, ab-initio electronic transport theory, electron spin resonance, various electrical defect spectroscopies, optical spectroscopy, positron annihilation spectroscopy and transmission electron microscopy. 
     We propose to undertake a highly synergistic approach with rigorous interaction and feedback loops between theory, materials synthesis, and characterization efforts to gain a comprehensive understanding of the materials science of β-Ga2O3.  The project is organized into three pillars of investigation composed of highly collaborative research tasks.  In Pillar 1, we will work towards definitively understanding intrinsic and extrinsic point defects and structural defects in terms of structure and properties.  In Pillar 2 we will develop methods for materials growth and processing to control defects produce heterostructures and study their properties.  In Pillar 3 we will investigate defects and transport especially in extreme conditions of temperature and field.
     We are aided by collaborations with Saint-Gobain and Synoptics in terms of crystal growth and characterization and with Dr. Joel Varley (LLNL) for theoretical insights.  Additionally, we will actively seek synergistic collaborations with researchers at DOE and DoD national labs and opportunities to leverage our proposal through user facilities.   
     This MURI project will uncover the fundamental potential and limitations of β-Ga2O3-based materials platform for kilovolt-class lateral power switch operation and megavolt-class vertical switches.