TY - JOUR
T1 - Evolution of threading dislocations in MOCVD-grown GaN films on (1 1 1) Si substrates
AU - Weng, X.
AU - Raghavan, S.
AU - Acord, J. D.
AU - Jain, A.
AU - Dickey, E. C.
AU - Redwing, J. M.
N1 - Funding Information:
This work was supported by The Penn State Electro-Optics Center, the Lehigh-Penn State Center for Optical Technologies, and the National Science Foundation under Grant Nos. ECS-0093742 and DMR-0606451.
Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2007/3/1
Y1 - 2007/3/1
N2 - We have quantitatively compared the evolution of threading dislocations (TDs) in GaN films grown on (1 1 1) Si substrates using different buffer/interlayer structures: a compositionally graded AlxGa1-xN (0≤x≤1) buffer layer, a thin high-temperature (HT) AlN interlayer (IL), and an AlN/GaN/AlxGa1-xN multilayer. Plan-view transmission electron microscopy (TEM) shows a reduction in TD density in GaN films grown on graded AlxGa1-xN buffer layers, and an increase in TD density in GaN films grown on HT AlN ILs, in comparison with those grown directly on an AlN buffer layer. Cross-sectional TEM reveals bending and annihilation of TDs within the graded AlxGa1-xN buffer layer, which lead to a decrease of TD density in the overgrown GaN films. On the other hand, a high density of TDs forms at the GaN/AlN IL interface, resulting in an increase in TD density in the GaN film. In addition, growing a thin AlN+GaN bilayer before growing the compositionally graded AlxGa1-xN buffer layer significantly reduces the TD density in the AlxGa1-xN buffer layer, which subsequently further reduces the TD density in the overgrown GaN film.
AB - We have quantitatively compared the evolution of threading dislocations (TDs) in GaN films grown on (1 1 1) Si substrates using different buffer/interlayer structures: a compositionally graded AlxGa1-xN (0≤x≤1) buffer layer, a thin high-temperature (HT) AlN interlayer (IL), and an AlN/GaN/AlxGa1-xN multilayer. Plan-view transmission electron microscopy (TEM) shows a reduction in TD density in GaN films grown on graded AlxGa1-xN buffer layers, and an increase in TD density in GaN films grown on HT AlN ILs, in comparison with those grown directly on an AlN buffer layer. Cross-sectional TEM reveals bending and annihilation of TDs within the graded AlxGa1-xN buffer layer, which lead to a decrease of TD density in the overgrown GaN films. On the other hand, a high density of TDs forms at the GaN/AlN IL interface, resulting in an increase in TD density in the GaN film. In addition, growing a thin AlN+GaN bilayer before growing the compositionally graded AlxGa1-xN buffer layer significantly reduces the TD density in the AlxGa1-xN buffer layer, which subsequently further reduces the TD density in the overgrown GaN film.
UR - http://www.scopus.com/inward/record.url?scp=33847270551&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33847270551&partnerID=8YFLogxK
U2 - 10.1016/j.jcrysgro.2006.11.030
DO - 10.1016/j.jcrysgro.2006.11.030
M3 - Article
AN - SCOPUS:33847270551
VL - 300
SP - 217
EP - 222
JO - Journal of Crystal Growth
JF - Journal of Crystal Growth
SN - 0022-0248
IS - 1
ER -