Advanced Designs for GaN-based Vertical IMPATT Diodes
Abstract
Abstract: GaN IMPATT (IMPact ionization Avalanche Transit-Time) diodes have the potential to revolutionize the generation of millimeter-wave frequency power generation, as a consequence of their anticipated absolute output power and conversion efficiency. The demonstration of true avalanche breakdown in GaN-on-GaN P-N junction diodes on low dislocation density substrates and the experimental extraction of the full impact ionization coefficients for both electrons and holes in low-defectivity GaN has established the enabling technological fundamentals for GaN IMPATT device development and demonstration. Our analysis, based on measurements of GaN vertical PN junctions, indicates that devices based on porting conventional IMPATT designs to the GaN material system will be limited by two key factors: access resistance and thermal dissipation. This project will alleviate both of these limitations by developing GaN-based IMPATT diodes with reduced thermal resistance and improved RF access resistance, achieved through a combination of fabrication process enhancements and device design modifications.This program aims to develop and demonstrate GaN-based IMPATT diodes for high-power microwave through millimeter-wave frequency generation, made possible by leveraging the state-of-the-art epitaxial material growth techniques, in combination with advanced fabrication process flows and unconventional anode structures for improved access resistance, and the use of our recently-demonstrated epitaxial lift-off and transfer process for improved thermal performance. The work leverages our assessments of the impact ionization coefficients of high quality GaN epitaxial structures and experimentally-calibrated numerical simulations of conventional Read-type IMPATT diodes, and proposes to combine it with our recent experimental studies of thermal resistance reductions for high-power GaN pn junctions. In addition, more sophisticated approaches to access resistance reductionincluding strain-induced hole transport enhancement and Schottky-injection IMPATT structuresare proposed to address the electrical access resistance limitations.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 29, 2020
- Source ID
- N000142012307
Entities
People
- Patrick Fay
Organizations
- Office of Naval Research
- United States Navy
- University of Notre Dame