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Title: Toward AlGaN channel HEMTs on AlN: Polarization-induced 2DEGs in AlN/AlGaN/AlN heterostructures
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.  more » « less
Award ID(s):
1719875
PAR ID:
10594732
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
American Institute of Physics
Date Published:
Journal Name:
APL Materials
Volume:
10
Issue:
11
ISSN:
2166-532X
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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