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Title: Strain relaxation in short-period polar GaN/AlN superlattices

Abstract

We have investigated the strain relaxation mechanisms in short-period polar GaN/AlN superlattices deposited by plasma-assisted molecular-beam epitaxy, and designed to display intersubband transitions at 1.55 mum. In a first stage, we have identified the growth conditions to minimize strain relaxation, using a Ga excess to reduce the (0001) surface free energy of both GaN and AlN. Under these growth conditions, crack propagation is not observed, even for the tensile-strained superlattices grown on GaN templates. The initial misfit relaxation in the vicinity of the buffer occurs by the formation of a-type dislocations. The final strain state of the superlattice, reached after 10-20 periods, is independent of the substrate (either GaN or AlN templates). Once the steady-state conditions are reached, we observe a periodic partial relaxation of quantum wells and barriers. High-resolution transmission electron microscopy indicates that the periodic relaxation can be related to the presence of basal and prismatic stacking faults creating clusters with an in-plane length of tens of nanometers. The effect of these defects on the optical performance of the superlattices is discussed by simulation of electronic structure using an 8x8kcentre dotp Schroedinger-Poisson solver. In the presence of basal stacking faults at the quantum well interfaces, the deviation ofmore » the e{sub 1}-e{sub 2} intersubband transition with respect to the nominal value is expected to be smaller than the measured absorption line width.« less

Authors:
; ;  [1];  [2];  [3]
  1. Equipe Mixte CEA-CNRS Nanophysique et Semiconducteurs, INAC/SP2M/NPSC, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)
  2. Equipe Mixte CEA-CNRS Nanophysique et Semiconducteurs, Institut Neel, 25 rue des Martyrs, 38042 Grenoble (France)
  3. CIMAP, CNRS-ENSICAEN-CEA-UCBN, 6 Boulevard du Marechal Juin, 14050 Caen Cedex (France)
Publication Date:
OSTI Identifier:
21359289
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 106; Journal Issue: 1; Other Information: DOI: 10.1063/1.3168431; (c) 2009 American Institute of Physics; Journal ID: ISSN 0021-8979
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION; ALUMINIUM NITRIDES; CRACK PROPAGATION; CRYSTAL GROWTH; DISLOCATIONS; ELECTRONIC STRUCTURE; GALLIUM NITRIDES; LINE WIDTHS; MOLECULAR BEAM EPITAXY; QUANTUM WELLS; SEMICONDUCTOR MATERIALS; SIMULATION; STACKING FAULTS; STEADY-STATE CONDITIONS; STRAINS; SUBSTRATES; SUPERLATTICES; SURFACE ENERGY; TENSILE PROPERTIES; TRANSMISSION ELECTRON MICROSCOPY; ALUMINIUM COMPOUNDS; CRYSTAL DEFECTS; CRYSTAL GROWTH METHODS; CRYSTAL STRUCTURE; ELECTRON MICROSCOPY; ENERGY; EPITAXY; FREE ENERGY; GALLIUM COMPOUNDS; LINE DEFECTS; MATERIALS; MECHANICAL PROPERTIES; MICROSCOPY; NANOSTRUCTURES; NITRIDES; NITROGEN COMPOUNDS; PHYSICAL PROPERTIES; PNICTIDES; SORPTION; SURFACE PROPERTIES; THERMODYNAMIC PROPERTIES

Citation Formats

Kandaswamy, P K, Jalabert, D, Monroy, E, Bougerol, C, and Ruterana, P. Strain relaxation in short-period polar GaN/AlN superlattices. United States: N. p., 2009. Web. doi:10.1063/1.3168431.
Kandaswamy, P K, Jalabert, D, Monroy, E, Bougerol, C, & Ruterana, P. Strain relaxation in short-period polar GaN/AlN superlattices. United States. doi:10.1063/1.3168431.
Kandaswamy, P K, Jalabert, D, Monroy, E, Bougerol, C, and Ruterana, P. Wed . "Strain relaxation in short-period polar GaN/AlN superlattices". United States. doi:10.1063/1.3168431.
@article{osti_21359289,
title = {Strain relaxation in short-period polar GaN/AlN superlattices},
author = {Kandaswamy, P K and Jalabert, D and Monroy, E and Bougerol, C and Ruterana, P},
abstractNote = {We have investigated the strain relaxation mechanisms in short-period polar GaN/AlN superlattices deposited by plasma-assisted molecular-beam epitaxy, and designed to display intersubband transitions at 1.55 mum. In a first stage, we have identified the growth conditions to minimize strain relaxation, using a Ga excess to reduce the (0001) surface free energy of both GaN and AlN. Under these growth conditions, crack propagation is not observed, even for the tensile-strained superlattices grown on GaN templates. The initial misfit relaxation in the vicinity of the buffer occurs by the formation of a-type dislocations. The final strain state of the superlattice, reached after 10-20 periods, is independent of the substrate (either GaN or AlN templates). Once the steady-state conditions are reached, we observe a periodic partial relaxation of quantum wells and barriers. High-resolution transmission electron microscopy indicates that the periodic relaxation can be related to the presence of basal and prismatic stacking faults creating clusters with an in-plane length of tens of nanometers. The effect of these defects on the optical performance of the superlattices is discussed by simulation of electronic structure using an 8x8kcentre dotp Schroedinger-Poisson solver. In the presence of basal stacking faults at the quantum well interfaces, the deviation of the e{sub 1}-e{sub 2} intersubband transition with respect to the nominal value is expected to be smaller than the measured absorption line width.},
doi = {10.1063/1.3168431},
journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 1,
volume = 106,
place = {United States},
year = {2009},
month = {7}
}