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Title: TEM studies of laterally overgrown GaN layers grown on non-polarsubstrates

Abstract

Transmission electron microscopy (TEM) was used to study pendeo-epitaxial GaN layers grown on polar and non-polar 4H SiC substrates. The structural quality of the overgrown layers was evaluated using a number of TEM methods. Growth of pendeo-epitaxial layers on polar substrates leads to better structural quality of the overgrown areas, however edge-on dislocations are found at the meeting fronts of two wings. Some misorientation between the 'seed' area and wing area was detected by Convergent Beam Electron Diffraction. Growth of pendeo-epitaxial layers on non-polar substrates is more difficult. Two wings on the opposite site of the seed area grow in two different polar directions with different growth rates. Most dislocations in a wing grown with Ga polarity are 10 times wider than wings grown with N-polarity making coalescence of these layers difficult. Most dislocations in a wing grown with Ga polarity bend in a direction parallel to the substrate, but some of them also propagate to the sample surface. Stacking faults formed on the c-plane and prismatic plane occasionally were found. Some misorientation between the wings and seed was detected using Large Angle Convergent Beam Diffraction.

Authors:
; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE; AFOSR ISSA 06NE001
OSTI Identifier:
920343
Report Number(s):
LBNL-60794
R&D Project: M70022; BnR: 400403109; TRN: US200818%%1145
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Conference
Resource Relation:
Conference: Photonic West SPIE-The International Society forOptical Engineering, San Jose, CA, 1/22-1-16/06
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; COALESCENCE; DIFFRACTION; DISLOCATIONS; ELECTRON DIFFRACTION; SEEDS; STACKING FAULTS; SUBSTRATES; TRANSMISSION ELECTRON MICROSCOPY

Citation Formats

Liliental-Weber, Z., Ni, X., and Morkoc, H.. TEM studies of laterally overgrown GaN layers grown on non-polarsubstrates. United States: N. p., 2006. Web.
Liliental-Weber, Z., Ni, X., & Morkoc, H.. TEM studies of laterally overgrown GaN layers grown on non-polarsubstrates. United States.
Liliental-Weber, Z., Ni, X., and Morkoc, H.. Thu . "TEM studies of laterally overgrown GaN layers grown on non-polarsubstrates". United States. doi:. https://www.osti.gov/servlets/purl/920343.
@article{osti_920343,
title = {TEM studies of laterally overgrown GaN layers grown on non-polarsubstrates},
author = {Liliental-Weber, Z. and Ni, X. and Morkoc, H.},
abstractNote = {Transmission electron microscopy (TEM) was used to study pendeo-epitaxial GaN layers grown on polar and non-polar 4H SiC substrates. The structural quality of the overgrown layers was evaluated using a number of TEM methods. Growth of pendeo-epitaxial layers on polar substrates leads to better structural quality of the overgrown areas, however edge-on dislocations are found at the meeting fronts of two wings. Some misorientation between the 'seed' area and wing area was detected by Convergent Beam Electron Diffraction. Growth of pendeo-epitaxial layers on non-polar substrates is more difficult. Two wings on the opposite site of the seed area grow in two different polar directions with different growth rates. Most dislocations in a wing grown with Ga polarity are 10 times wider than wings grown with N-polarity making coalescence of these layers difficult. Most dislocations in a wing grown with Ga polarity bend in a direction parallel to the substrate, but some of them also propagate to the sample surface. Stacking faults formed on the c-plane and prismatic plane occasionally were found. Some misorientation between the wings and seed was detected using Large Angle Convergent Beam Diffraction.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jan 05 00:00:00 EST 2006},
month = {Thu Jan 05 00:00:00 EST 2006}
}

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  • Transmission electron microscopy was used to study defects in lateral epitaxial layers of GaN which were overgrown on a template of a-plane (11{und 2}0) GaN grown on (1{und 1}02) r-plane Al2O3. A high density of basal stacking faults is formed in these layers because the c-planes of wurtzite structure are arranged along the growth direction. Density of these faults is decreasing at least by two orders of magnitude lower in the wings compared to the seed areas. Prismatic stacking faults and threading dislocations are also observed, but their densities drastically decrease in the wings. The wings grow with opposite polaritiesmore » and the Ga-wing width is at least 6 times larger than N-wing and coalescence is rather difficult. Some tilt and twist was detected using Large Angle Convergent Beam Electron Diffraction.« less
  • No abstract prepared.
  • Transmission electron microscopy study of plan-view and cross-section samples of epitaxial laterally overgrown (ELOG) GaN samples is described. Two types of dislocation with the same type of Burgers vector but different line direction have been observed. It is shown that threading edge dislocations bend to form dislocation segments in the c plane as a result of shear stresses developed in the wing material along the stripe direction. It is shown that migration of these dislocations involves both glide and climb. Propagation of threading parts over the wing area is an indication of high density of point defects present in themore » wing areas on the ELOG samples. This finding might shed light on the optical properties of such samples. {copyright} 2001 American Institute of Physics.« less
  • Transmission electron microscopy study of plan-view and cross-section samples of epitaxial laterally overgrown (ELOG) GaN samples is described. Two types of dislocation with the same type of Burgers vector but different line direction have been observed. It is shown that threading edge dislocations bend to form dislocation segments in the c-plane as a result of shear stresses developed in the wing material along the stripe direction. It is shown that migration of these dislocations involves both glide and climb. Propagation of threading parts over the wing area is an indication of high density of point defects present in the wingmore » areas on the ELOG samples. This finding might shed new light on the optical properties of such samples.« less
  • No abstract prepared.