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Very low dislocation density, resistive GaN films obtained using transition metal nitride interlayers
Author(s) -
Moram M. A.,
Kappers M. J.,
Zhang Y.,
Barber Z. H.,
Humphreys C. J.
Publication year - 2008
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.200778608
Subject(s) - materials science , dislocation , nitride , amorphous solid , metalorganic vapour phase epitaxy , sapphire , optoelectronics , layer (electronics) , pinhole (optics) , resistive touchscreen , composite material , crystallography , epitaxy , optics , laser , chemistry , physics , electrical engineering , engineering
A threading dislocation density (TDD) reduction method for GaN films is described. Thin amorphous layers of Sc, Hf, Nb, Zr and Cr were deposited on MOVPE‐grown GaN‐on‐sapphire templates with a TDD of 5 × 10 9 cm –2 and annealed in NH 3 to form metal nitrides. The ScN layer remained continuous, with a very low pinhole density, while the HfN layer contained a high pinhole density of approximately 3 × 10 9 cm –2 . The NbN and ZrN layers formed oriented holey network structures. The Cr layer did not nitride. Coalesced GaN epilayers grown on the ScN layers had the lowest dislocation density of 3 × 10 7 cm –2 (un‐coalesced GaN on ScN had TDDs as low as 5 × 10 6 cm –2 ). Unlike GaN films grown using multiple SiN x interlayers, which contain a similar proportion of edge and mixed dislocations, the GaN‐on‐ScN layers contain substantially fewer mixed than edge dislocations, a proportion similar to that of the high‐TDD template. The low‐TDD GaN epilayers grown on ScN are also highly electrically resistive. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)