Leveraging a New Theoretical Paradigm to Enhance Interfacial Thermal Transport In Wide Bandgap Power Electronics
Abstract
The development of wide bandgap electronics is poised to impact future RF and advanced power electronic switches needed for numerous DoD applications. The performance and reliability of these devices will be impacted by their electrothermal response. Therefore, efficient heat dissipation is necessary in order to maintain reasonable device temperatures. The temperature rise in these devices is governed, in part, by the thermal boundary conductance (TBC) at interfaces associated with the device structure. Increasing the TBC at interfaces in these electronics has only been attempted in limited research studies, using Edisonian approaches, because knowledge of the fundamental scientific mechanisms governing TBC are lacking. Our theoretical understanding has been based on the widely accepted phonon gas model (PGM), which frequently fails to explain experimental data. Most models lack predictive capability, which is needed to design thermal interfaces. In addition, understanding the effects of disorder and structure at interfaces is necessary to broaden our understanding of pathways to effectively increase TBC at device interfaces. Thus, our proposal will utilize a new theoretical paradigm to investigate phonon transport and the modes that develop at the interface between two adjoining materials, which can contribute significantly to TBC. This method will be an improvement over previous PGM based models, which lack the ability to capture such interfacial effects, and are limited in their ability to accurately describe TBC. We will use a combination of our new theoretical approach and experimental knowledgebase of GaN devices to guide the interfacial thermal engineering of thermal interfaces in GaN and Ga2O3 for the first time (metalsemiconductor and semiconductor-semiconductor/dielectric interfaces). We will also use our team???s expertise to advance the thermal metrology of TBC in these materials with reduced uncertainty, even for buried interfaces. In parallel, we will perform detailed characterization of the structure of these interfaces in order to help explain the physical origins of TBC. Unique to this is effort is the use of a recent capability based on high energy resolution EELS-STEM which can measure phonon vibrational energies with high spatial resolution. This will allow us to measure the extent and frequency of interfacial phonons around defects and dopants near the interface. We will utilize our team???s expertise in growth to carefully fabricate samples through MOCVD, MBE, and layer transfer bonding in order to create interfaces with the highest control over structure and composition. In addition, we will implement our methods to increase TBC in GaN based power electronic devices in lateral devices (short term) and implement a major focus on vertical, high voltage - high current devices. The team will be led by PI Samuel Graham from the Georgia Institute of Technology along with Prof. Asegun Henry (modeling) and Prof. Alan Doolittle (MBE growth). Others involved with include Prof. Patrick Hopkins (University of Virginia, thermal measurements), Prof. Tengfei Luo (Notre Dame, modeling and measurements), Prof. Asif Khan (South Carolina, MOCVD growth), and Prof Mark Goorsky (UCLA, materials characterization). In addition, we will work with a diverse set of partners and collaborators to maximize program successful, including Northrop Grumman, Oak Ridge National Labs, Prof.Hiroshi Amano (Nagoya University), Prof. Martin Kuball (University of Bristol), Ken Goodson (Stanford), and Prof. Junichiro Shiomi (University of Tokyo). The impact of this work on DoD systems will be the development and demonstration of GaN/AlGaN based vertical power devices with >5 kV operation and high TBC thermal interfaces that improve device reliability.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 26, 2018
- Source ID
- N000141812429
Entities
People
- Samuel Graham
Organizations
- Georgia Tech Research Corporation
- Office of Naval Research
- United States Navy