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Bandgap Tailoring of Monoclinic Single‐Phase β‐(Al x Ga 1− x ) 2 O 3 (0 ≤ x ≤ 0.65) Thin Film by Annealing β‐Ga 2 O 3 /Al 2 O 3 Heterojunction at High Temperatures
Author(s) -
Li Zhengcheng,
Wu Ying,
Feng Boyuan,
Li Yao,
Liu Tong,
Feng Jiagui,
Chen Xiao,
Huang Rong,
Xu Leilei,
Li Zhiyun,
Hu Nan,
Li Fangsen,
Jia Zhitai,
Niu Gang,
Guo Qixin,
He Gaohang,
Ding Sunan
Publication year - 2021
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.202000785
Subject(s) - monoclinic crystal system , x ray photoelectron spectroscopy , materials science , heterojunction , thin film , band gap , annealing (glass) , analytical chemistry (journal) , molecular beam epitaxy , epitaxy , crystallography , optoelectronics , nanotechnology , crystal structure , chemistry , nuclear magnetic resonance , physics , metallurgy , chromatography , layer (electronics)
Herein, bandgap tuning of monoclinic (−201)‐oriented β‐(Al x Ga 1− x ) 2 O 3 thin films is achieved through a β‐Ga 2 O 3 /Al 2 O 3 heterojunction by a feasible annealing process with an O 2 atmosphere. During the annealing process, Al atoms of the Al 2 O 3 substrate outdiffuse easily into the β‐Ga 2 O 3 thin film deposited by ozone‐assisted molecular beam epitaxy (OMBE). The Al compositions in the β‐(Al x Ga 1− x ) 2 O 3 samples are tuned through adjusting the annealing temperature from 800 to 1300 °C and experimentally determined from the result of X‐ray photoelectron spectroscopy (XPS) measurements combined with Vegard's law. Successive Al‐composition‐gradient β‐(Al x Ga 1− x ) 2 O 3 thin films with controlled bandgap are constructed. On these bases, β‐Ga 2 O 3 thin films are deposited on β‐(Al x Ga 1− x ) 2 O 3 (0 ≤ x ≤ 0.65) substrates through OMBE, yielding β‐Ga 2 O 3 /β‐(Al x Ga 1− x ) 2 O 3 (0 ≤ x ≤ 0.65) heterojunction structures, and the band offsets of this heterojunction are determined by XPS accordingly. This methodology to achieve high‐quality β‐(Al x Ga 1− x ) 2 O 3 thin films with adjustable Al composition and tunable band offsets of the β‐Ga 2 O 3 /β‐(Al x Ga 1− x ) 2 O 3 interface will provide guidance for potential strategies to develop and fabricate β‐(Al x Ga 1− x ) 2 O 3 ‐based deep‐UV photodetectors and power devices.