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Semipolar ( 11 2 ¯ 2 ) GaN Films Improved by in situ SiN x Pretreatment of m‐Sapphire Substrate Surface
Author(s) -
Wu Zhengyuan,
Jiang Zhuoxun,
Lu Shiqiang,
Li Jinchai,
Liu Ran,
Kang Junyong,
Fang Zhilai
Publication year - 2019
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.201900001
Subject(s) - cathodoluminescence , materials science , nucleation , coalescence (physics) , sapphire , x ray photoelectron spectroscopy , substrate (aquarium) , raman spectroscopy , in situ , crystallography , analytical chemistry (journal) , optoelectronics , optics , luminescence , chemical engineering , chemistry , laser , physics , oceanography , organic chemistry , chromatography , astrobiology , geology , engineering
The authors report on growth and characterization of semipolar ( 11 2 ¯ 2 ) GaN films improved by an in situ SiN x pretreatment of m‐sapphire substrate surface. Formation of SiN x and Ga‐rich surface at the initial growth stages is evidenced by X‐ray photoelectron spectroscopy. With the SiN x pretreatment, the GaN nucleated island density decreases due to the reduction of nucleation density by the SiN x mask. X‐ray diffraction and Raman analyses show reduction of threading defect density for the SiN x pretreated GaN films. Cathodoluminescence studies show enhanced D 0 X emission and suppressed defect‐related emissions. The improvements in crystalline quality and optical properties of semipolar GaN films with the SiN x pretreatment are attributed to the reduction in nucleated island density and coalescence boundaries, and enhancement of the +c island sidewall facet growth under Ga‐rich growth conditions.