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Toward AlGaN channel HEMTs on AlN: Polarization-induced 2DEGs in AlN/AlGaN/AlN heterostructures

Journal Article · · APL Materials
DOI:https://doi.org/10.1063/5.0121195· OSTI ID:2421816
 [1];  [2];  [2];  [2];  [2];  [2]
  1. Cornell Univ., Ithaca, NY (United States); Cornell Univ., Ithaca, NY (United States)
  2. Cornell Univ., Ithaca, NY (United States)
+ Show Author Affiliations

Due to its high breakdown electric field, the ultra-wide bandgap semiconductor AlGaN has garnered much attention recently as a promising channel material for next-generation high electron mobility transistors (HEMTs). A comprehensive experimental study of the effects of Al composition x on the transport and structural properties is lacking. We report the charge control and transport properties of polarization-induced 2D electron gases (2DEGs) in strained AlGaN quantum well channels in molecular-beam-epitaxy-grown AlN/AlxGa1-xN/AlN double heterostructures by systematically varying the Al content from x = 0 (GaN) to x = 0.74, spanning energy bandgaps of the conducting HEMT channels from 3.49 to 4.9 eV measured by photoluminescence. This results in a tunable 2DEG density from 0 to 3.7 × 1013 cm2. The room temperature mobilities of x ≥ 0.25 AlGaN channel HEMTs were limited by alloy disorder scattering to below 50 cm2/(V.s) for these 2DEG densities, leaving ample room for further heterostructure design improvements to boost mobilities. A characteristic alloy fluctuation energy of ≥1.8 eV for electron scattering in AlGaN alloy is estimated based on the temperature dependent electron transport experiments.

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:
2421816
Alternate ID(s):
OSTI ID: 1899637
Journal Information:
APL Materials, Journal Name: APL Materials Journal Issue: 11 Vol. 10; ISSN 2166-532X
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English

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Figures / Tables (7)

FIG. 1(p. 4)figure FIG. 1
FIG. 2(p. 4)figure FIG. 2
FIG. 3(p. 5)figure FIG. 3
FIG. 4(p. 5)figure FIG. 4
FIG. 5(p. 6)figure FIG. 5
TABLE I(p. 6)table TABLE I
FIG. 6(p. 7)figure FIG. 6

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Related Subjects

36 MATERIALS SCIENCE
Electron gas
Electron scattering
Electronic transport
Epitaxy
Field effect transistors
Heterostructures
Photoluminescence
Quantum wells
Semiconductors
Transport properties