Record >10 MV/cm mesa breakdown fields in Al0.85Ga0.15N/Al0.6Ga0.4N high electron mobility transistors on native AlN substrates
Abstract
The ultra-wide bandgap of Al-rich AlGaN is expected to support a significantly larger breakdown field compared to GaN, but the reported performance thus far has been limited by the use of foreign substrates. In this Letter, the material and electrical properties of Al0.85Ga0.15N/Al0.6Ga0.4N high electron mobility transistors (HEMT) grown on a 2-in. single crystal AlN substrate are investigated, and it is demonstrated that native AlN substrates unlock the potential for Al-rich AlGaN to sustain large fields in such devices. We further study how Ohmic contacts made directly to a Si-doped channel layer reduce the knee voltage and increase the output current density. High-quality AlGaN growth is confirmed via scanning transmission electron microscopy, which also reveals the absence of metal penetration at the Ohmic contact interface and is in contrast to established GaN HEMT technology. Two-terminal mesa breakdown characteristics with 1.3 μm separation possess a record-high breakdown field strength of ∼11.5 MV/cm for an undoped Al0.6Ga0.4N-channel layer. The breakdown voltages for three-terminal devices measured with gate-drain distances of 4 and 9 μm are 850 and 1500 V, respectively.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Apr 25, 2022
- Source ID
- 10.1063/5.0083966
Entities
People
- Dolar Khachariya
- Erhard Kohn
- J. Houston Dycus
- M. Hayden Breckenridge
- Pegah Bagheri
- Pramod Reddy
- Ramón Collazo
- Rohan Sengupta
- Ronny Kirste
- Saroj Dangi
- Seiji Mita
- Shashwat Rathkanthiwar
- Spyridon Pavlidis
- Zlatko Sitar
Organizations
- Air Force Office of Scientific Research
- Army Research Office
- National Science Foundation
- North Carolina State University
- United States Department of Energy