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Tuning Electrical and Thermal Transport in AlGaN/GaN Heterostructures via Buffer Layer Engineering

Title
Tuning Electrical and Thermal Transport in AlGaN/GaN Heterostructures via Buffer Layer Engineering
Author
소홍윤
Keywords
2DEG; AlGaN/GaN; polarization; Seebeck coefficients; thermal conductivity
Issue Date
2018-05
Publisher
WILEY-V C H VERLAG GMBH
Citation
ADVANCED FUNCTIONAL MATERIALS, v. 28, no. 22, Article no. 1705823
Abstract
Progress in wide bandgap, III-V material systems based on gallium nitride (GaN) has enabled the realization of high-power and high-frequency electronics. Since the highly conductive, 2D electron gas (2DEG) at the aluminum gallium nitride (AlGaN)/GaN interface is based on built-in polarization fields and is confined to nanoscale thicknesses, its charge carriers exhibit much higher mobilities compared to their doped counterparts. This study shows that such 2DEGs also offer the unique ability to manipulate electrical transport separately from thermal transport, through the examination of fully suspended AlGaN/GaN diaphragms of varied GaN buffer layer thickness. Notably, approximate to 100 nm thin GaN layers can considerably impede heat flow without electrical transport degradation. These achieve 4x improvement in the thermoelectric figure of merit (zT) over externally doped GaN, with state-of-the-art power factors of 4-7 mW m(-1) K-2. The remarkable tuning behavior and thermoelectric enhancement, elucidated here for the first time in a polarization-based heterostructure, are achieved because electrons are at the heterostructured interface, while phonons are within the material system. These results highlight the potential for using 2DEGs in III-V materials for on-chip thermal sensing and energy harvesting.
URI
https://onlinelibrary.wiley.com/doi/abs/10.1002/adfm.201705823https://repository.hanyang.ac.kr/handle/20.500.11754/118557
ISSN
1616-301X; 1616-3028
DOI
10.1002/adfm.201705823
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > MECHANICAL ENGINEERING(기계공학부) > Articles
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