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Impact of Plasma‐Damaged‐Layer Removal on GaN HEMT Devices
Author(s) -
Kodera Masako,
Yoshioka Akira,
Sugiyama Toru,
Ohguro Tatsuya,
Hamamoto Takeshi,
Kawamoto Tatsuyoshi,
Yamanaka Tatsuya,
Xinyu Zhang,
Lester Steve,
Miyashita Naoto
Publication year - 2018
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201700633
Subject(s) - materials science , dry etching , x ray photoelectron spectroscopy , amorphous solid , high electron mobility transistor , layer (electronics) , etch pit density , surface roughness , plasma , analytical chemistry (journal) , plasma etching , optoelectronics , etching (microfabrication) , chemical engineering , transistor , composite material , chemistry , voltage , crystallography , electrical engineering , chromatography , physics , quantum mechanics , engineering
Plasma‐damage during the dry‐etch process often induces degradation of the electric performance in GaN high electron mobility transistor (HEMT) devices. In this paper, the effects of wet‐etch processing on plasma‐damaged AlGaN films using various chemical solutions and propose the best chemical formulation are reported. Three chemical solutions are selected by a combinatorial method. A MIS‐capacitor TEG is fabricated on an AlGaN/GaN structure, and each surface is evaluated by XPS, SIMS, TEM, and AFM. From the results of C–V measurements of wet‐etched samples, the study reveals that the wet chemicals successfully remove charge traps at ≈−2.3 eV induced by the dry‐etch process. Moreover, these C–V results show excellent agreement with simulated trap models. The XPS results show that O/Ga ratios increase from 0.32 to 1.00 after the dry‐etch process, whereas after the wet‐etch process, the ratios return to less than 0.31. Moreover, the TEM observations reveal that an amorphous layer is only detected in the dry‐etched sample. Therefore, this amorphous layer should be an oxidized AlGaN layer. Thus, the selected chemical formulation can successfully remove the damaged‐layer induced by the dry‐etch process. The increase of surface roughness by the wet‐etch process is suppressed less than 0.1 nm.