Polarization-induced 2D electron gases in N-polar AlGaN/AlN heterostructures on single-crystal AlN substrates
Abstract
Polarization-induced carriers play an important role in achieving high electrical conductivity in ultrawide bandgap semiconductor AlGaN, which is essential for various applications ranging from radio frequency and power electronics to deep UV photonics. Despite significant scientific and technological interest, studies on polarization-induced carriers in N-polar AlGaN are rare. We report the observation and properties of polarization-induced two-dimensional electron gases (2DEGs) in N-polar AlGaN/AlN heterostructures on single-crystal AlN substrates by systematically varying the Al content in the 8 nm top layers from x = 0 to x = 0.6, spanning energy bandgaps from 3.56 to 4.77 eV. The 2DEG density drops monotonically with increasing Al content, from 3.8 × 1013/cm2 in the GaN channel, down to no measurable conductivity for x = 0.6. Alloy scattering limits the 2DEG mobility to below 50 cm2/V s for x = 0.49. These results provide valuable insights for designing N-polar AlGaN channel high electron mobility transistors on AlN for extreme electronics at high voltages and high temperatures, and for UV photonic devices.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- May 22, 2023
- Source ID
- 10.1063/5.0145826
Entities
People
- Debdeep Jena
- Eungkyun Kim
- Huili Grace Xing
- Jashan Singhal
- Masato Toita
- Shivali Agrawal
- Vladimir Protasenko
- Zexuan Zhang
Organizations
- Air Force Office of Scientific Research
- Army Research Office
- Asahi Kasei
- Cornell University
- Office of Basic Energy Sciences