ABSTRACT

Proposal Number: 2043803
Principal Investigator: Elaheh Ahmadi,
Title: CAREER: A novel Gallium Oxide based transistor for low-waste power conversion applications
Institution: University of Michigan

Nontechnical Abstract
There is an urgent need for new device technologies to efficiently manage and distribute electrical power in the 2000V-20000V voltage range. The current technology, however, can no longer meet the efficiency and reliability requirements for these high-power electronic applications. The proposed ultra-high voltage switch will enable efficient high-power switches in the 2000V-20000V voltage range, which is required in many systems, including distributed grid systems, industrial automation, electric vehicles, and electrical mass transit including high-speed trains. The integrated education plan aims to motivate young students, especially female students and those from the underrepresented groups, to pursue STEM studies and careers by direct participation in the proposed research activities. The tutorials prepared for high school students will be made widely available on PI?s research website and YouTube. The scientific results will be disseminated in the form of articles in technical journals, conference presentations, and university seminars.

Technical Abstract
The goal of this program is to demonstrate E-mode ?-Ga2O3 fin field-effect transistors (FinFETs) with breakdown voltages beyond 3kV, specific on-resistance lower than 1 milli-ohm-cm-square switching efficiency higher than 98% at 15kHz frequency. The scientific goals of this CAREER plan are (i) A thorough investigation and experimentation into the impact of slanted-sidewall and N implantation in the inter-fin areas on electric fields to enhance breakdown voltage. (ii) Fabrication and characterization of FinFETs on both metal-organic chemical vapor deposition (MOCVD)-grown and halide vapor phase epitaxy (HVPE)-grown epi-structure to analyze and compare the impact of growth technique, and material quality on device performance. This study assists in selecting the appropriate growth technique for each process module in the future. (iii) A systematic study of the substrate thickness impact on device characteristics such as Ron. (iv) Development of ?-(Al,Ga)2O3 regrowth on the fin sidewalls by plasma-assisted molecular beam epitaxy (PAMBE) and a complete investigation of the impact of regrowth conditions on electron mobility in the channel, interface trap density, and FinFET characteristics. This will be the first demonstration of sidewall regrowth in this material system. (v) Development of robust and reliable Hf(Si)O2 dielectrics by PAMBE as well as investigation and analysis of deposition conditions on dielectric quality (breakdown, dielectric constant, leakage, etc.). This will be the first demonstration of in-situ dielectric deposition in this material system.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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