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High‐Quality AlN Template Prepared by Face‐to‐Face Annealing of Sputtered AlN on Sapphire
Author(s) -
Shojiki Kanako,
Uesugi Kenjiro,
Kuboya Shigeyuki,
Inamori Takafumi,
Kawabata Shin,
Miyake Hideto
Publication year - 2021
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.202000352
Subject(s) - metalorganic vapour phase epitaxy , materials science , sapphire , epitaxy , annealing (glass) , wafer , optoelectronics , analytical chemistry (journal) , composite material , laser , optics , chemistry , layer (electronics) , chromatography , physics
This study comprehensively investigates the properties of metalorganic vapor phase epitaxy (MOVPE)‐grown AlN films on high‐quality face‐to‐face annealed sputtered AlN (FFA Sp‐AlN) templates on sapphire substrates, which are highly important to control the surface morphology for various applications, such as UV light‐emitting diodes and laser diodes. The conditions of thermal cleaning and AlN growth by MOVPE are investigated to remove numerous small islands on as‐annealed FFA Sp‐AlN. Subsequent to thermal cleaning in H 2 + NH 3 at 1300 °C, MOVPE growth is performed with varying NH 3 flow rate and growth temperature ( T g ) under a constant pressure and group‐III flow rate. An atomically flat surface with an atomic step‐and‐terrace structure is obtained at a growth rate of ≈1.0 μm h −1 and a T g of 1300 °C. Transmission electron microscopy images and secondary‐ion mass spectrometry reveal low dislocation densities and impurity concentrations. Finally, the effects of compressive strain in FFA Sp‐AlN on the lattice constant and curvature of the MOVPE‐grown AlN film on FFA Sp‐AlN are investigated. The compressive strain of the AlN film, which is carried over from FFA Sp‐AlN, can prevent crack formation but leads to a large wafer curvature after cooling down from the T g .