Potential and challenges in gallium oxide, the next generation power semiconductor technology

The combined Santa Clara Valley, San Francisco, & Oakland/East Bay IEEE PELS is very pleased to invite you to our upcoming in-person event. We are excited and honored to have Prof. Uttam Singisetti of the University at Buffalo to speak on the topic of Potential and challenges in gallium oxide, the next generation power semiconductor technology.
Here's more about the talk from the Speaker:
The monoclinic -gallium oxide (Ga2O3) (bandgap 4.8 eV) is one of several ultra-widebandgap semiconductors (UWBGs) that have garnered a lot of interest as next generation power semiconductor technology. Since the first demonstration of a MESFET in 2012, Ga2O3 device research has progressed at an incredible pace with reports of MOSFETs and diodes achieving 10 kV breakdown voltages. Gallium oxide devices have also achieved impressive high power device figure of merit, high average field strengths and high-speed performance. The high critical electric field, good electron mobility, multiple shallow donors, availability of large area substrates and growth of high-quality epitaxial films; have all contributed to the rapid progress in device performance. As a result, it has emerged as a promising ultra-widebandgap semiconductor for next generation power, GHz switching and RF applications. In addition to the large Baliga’s Figure of Merit (BFoM); good electron mobility, calculated electron velocities lead to higher Johnston’s Figures of Merit (JFoM). Additionally, the large bandgap also enables high temperature operation and radiation hardness making it attractive for space applications such as Mars and Venus missions. This talk will present the most recent advances in gallium oxide devices; both from our group and others. We will present the lateral MOSFETs with improved field plate design and beyond-kV breakdown. Temperature dependent analysis and device simulation suggest an extrinsic breakdown mechanism outside the channel. A simple and yet effective SU-8 polymer passivation technology provides a significant improvement in breakdown voltages. The higher field strength of the SU-8 polymer enables a significant increase in breakdown voltage to 8.5 kV in lateral MOSFETs. However, these devices show a high Ron, which is due to the depletion caused by RIE of the channel. We will present the use of ultra-high vacuum annealing techniques to improve the on-resistance of the devices still maintaining the multi-kilo-volt rating of the devices. We will also present on-wafer individual device level switching characteristics. I will discuss the progress made on vertical Schottky barrier diodes (SBDs) which have rapidly achieved both high voltages and high-power deice figures of merit. Several groups have incorporated nickel-oxide/gallium oxide hetero-junction p-n diodes to successfully overcome the absence of p-doping in gallium oxide. High surge-current capability and unclamped inductive switching (UIS) have been demonstrated in these devices despite the low thermal conductivity. Finally, I will discuss the approaches that could address the challenges in this semiconductor system (low thermal conductivity and absence of p-doping). I will conclude by discussing the factors that could potentially lead to successful lab-to-fab transition in this exciting next generation power semiconductor technology.
Speaker(s): , Dr. Uttam Singisetti
Plug and Play Tech Center, 440 N Wolfe Rd, Sunnyvale, California, United States, 94085