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High-density polarization-induced 2D electron gases in N-polar pseudomorphic undoped GaN/Al0.85Ga0.15N heterostructures on single-crystal AlN substrates

Journal Article · · Applied Physics Letters
DOI:https://doi.org/10.1063/5.0107159· OSTI ID:1979149
 [1];  [2];  [2];  [2];  [2];  [2];  [3];  [4];  [4]
  1. Cornell Univ., Ithaca, NY (United States); Cornell Univ., Ithaca, NY (United States)
  2. Cornell Univ., Ithaca, NY (United States)
  3. Asahi Kasei Corporation, Tokyo (Japan)
  4. Cornell Univ., Ithaca, NY (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY (United States)
+ Show Author Affiliations

The polarization difference and band offset between Al(Ga)N and GaN induce two-dimensional (2D) free carriers in Al(Ga)N/GaN heterojunctions without any chemical doping. A high-density 2D electron gas (2DEG), analogous to the recently discovered 2D hole gas in a metal-polar structure, is predicted in a N-polar pseudomorphic GaN/Al(Ga)N heterostructure on unstrained AlN. We report the observation of such 2DEGs in N-polar undoped pseudomorphic GaN/AlGaN heterostructures on single-crystal AlN substrates by molecular beam epitaxy. With a high electron density of ~4.3 ×1013/cm2 that maintains down to cryogenic temperatures and a room temperature electron mobility of ~450 cm2/V s, a sheet resistance as low as ~320 Ω/$$\Box$$ is achieved in a structure with an 8 nm GaN layer. Finally, these results indicate significant potential of AlN platform for future high-power RF electronics based on N-polar III-nitride high electron mobility transistors.

Research Organization:
Arizona State Univ., Tempe, AZ (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF); US Air Force Office of Scientific Research (AFOSR)
Grant/Contract Number:
SC0021230
OSTI ID:
1979149
Alternate ID(s):
OSTI ID: 1883635
Journal Information:
Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 8 Vol. 121; ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English

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Related Subjects

42 ENGINEERING
Electron diffraction
Electron gas
Electronic transport
Epitaxy
Field effect transistors
Hall effect
Heterostructures
High mobility electron gas
Semiconductors