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Heteroepitaxial β‐Ga 2 O 3 on Conductive Ceramic Templates: Toward Ultrahigh Gain Deep‐Ultraviolet Photodetection
Author(s) -
Alfaraj Nasir,
Li KuangHui,
Alawein Meshal,
Kang Chun Hong,
Braic Laurentiu,
Zoita Nicolae Catalin,
Kiss Adrian Emil,
Ng Tien Khee,
Ooi Boon S.
Publication year - 2021
Publication title -
advanced materials technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.184
H-Index - 42
ISSN - 2365-709X
DOI - 10.1002/admt.202100142
Subject(s) - materials science , photodetection , tin , nucleation , responsivity , ultraviolet , ceramic , crystallography , crystal (programming language) , optoelectronics , monoclinic crystal system , crystal structure , photodetector , composite material , chemistry , metallurgy , organic chemistry , computer science , programming language
Abstract This article investigates the ultrahigh sensitivity and DUV photodetection capability of a hybrid oxide‐nitride stack comprising β‐Ga 2 O 3 layers grown heterogeneously on a conductive ceramic crystal. The ceramic crystal, namely a TiN interlayer, which acts as a lattice template, was heteroepitaxially grown on bulk MgO. Because β‐Ga 2 O 3 is a monoclinic phase crystal, it is conjectured that its nucleation and growth process on cubic phase TiN is entropic in nature, whereby the two unit cell configurations of the β‐Ga 2 O 3 crystal, exhibiting rotational twin domains, grew alternately side by side in a semiperiodic manner on TiN while maintaining a single crystal phase. This film formation mechanism contributed to the introduction of additional defects in the β‐Ga 2 O 3 lattice (Taylor's dislocations in addition to growth‐induced vacancies). The fabricated DUV photodetectors based on the resulting metal‐semiconductor junction heterodiodes exhibited an average peak spectral responsivity of 276.72 A W −1 and fast decay constants in the order of 500 ms in the ultraviolet‐C regime, with true solar‐blind characteristics manifested by ultraviolet‐to‐visible rejection ratios of up to 2 × 10 3 and illuminating power density of around 70 μW cm −2 . The crystallographic orientation relationships between the TiN and β‐Ga 2 O 3 crystals, as well as the lattice fit and dislocation types, are revealed and examined.