skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Nonlinear Evolution of Surface Morphology in InAs/AlAs Superlattices via Surface Diffusion

Abstract

Continuum simulations of self-organized lateral compositional modulation growth in InAs/AlAs short-period superlattices on InP substrate are presented. The results of the simulations correspond quantitatively to the results of synchrotron x-ray diffraction experiments. The time evolution of the compositional modulation during epitaxial growth can be explained only including a nonlinear dependence of the elastic energy of the growing epitaxial layer on its thickness. From the fit of the experimental data to the growth simulations we have determined the parameters of this nonlinear dependence. It was found that the modulation amplitude does not depend on the values of the surface diffusion constants of particular elements.

Authors:
 [1];  [2];  [3]
  1. Institute of Condensed Matter Physics, Masaryk University, Kotlarska 2, 61137 Brno (Czech Republic)
  2. Department of Electronic Structures, Charles University, Prague (Czech Republic)
  3. Department of Physics, University of Houston, Houston, Texas 77204-5005 (United States)
Publication Date:
OSTI Identifier:
20777135
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 96; Journal Issue: 13; Other Information: DOI: 10.1103/PhysRevLett.96.136102; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM ARSENIDES; CRYSTAL GROWTH; DIFFUSION; EVOLUTION; EXPERIMENTAL DATA; INDIUM ARSENIDES; INDIUM PHOSPHIDES; LAYERS; MODULATION; MOLECULAR BEAM EPITAXY; MORPHOLOGY; NONLINEAR PROBLEMS; SEMICONDUCTOR MATERIALS; SIMULATION; SUBSTRATES; SUPERLATTICES; THICKNESS; X-RAY DIFFRACTION

Citation Formats

Caha, O., Holy, V., and Bassler, Kevin E. Nonlinear Evolution of Surface Morphology in InAs/AlAs Superlattices via Surface Diffusion. United States: N. p., 2006. Web. doi:10.1103/PhysRevLett.96.136102.
Caha, O., Holy, V., & Bassler, Kevin E. Nonlinear Evolution of Surface Morphology in InAs/AlAs Superlattices via Surface Diffusion. United States. doi:10.1103/PhysRevLett.96.136102.
Caha, O., Holy, V., and Bassler, Kevin E. Fri . "Nonlinear Evolution of Surface Morphology in InAs/AlAs Superlattices via Surface Diffusion". United States. doi:10.1103/PhysRevLett.96.136102.
@article{osti_20777135,
title = {Nonlinear Evolution of Surface Morphology in InAs/AlAs Superlattices via Surface Diffusion},
author = {Caha, O. and Holy, V. and Bassler, Kevin E.},
abstractNote = {Continuum simulations of self-organized lateral compositional modulation growth in InAs/AlAs short-period superlattices on InP substrate are presented. The results of the simulations correspond quantitatively to the results of synchrotron x-ray diffraction experiments. The time evolution of the compositional modulation during epitaxial growth can be explained only including a nonlinear dependence of the elastic energy of the growing epitaxial layer on its thickness. From the fit of the experimental data to the growth simulations we have determined the parameters of this nonlinear dependence. It was found that the modulation amplitude does not depend on the values of the surface diffusion constants of particular elements.},
doi = {10.1103/PhysRevLett.96.136102},
journal = {Physical Review Letters},
number = 13,
volume = 96,
place = {United States},
year = {Fri Apr 07 00:00:00 EDT 2006},
month = {Fri Apr 07 00:00:00 EDT 2006}
}
  • The nature of spontaneous lateral composition modulation and its relationship to surface morphology during the growth of (AlAs){sub m}(InAs){sub n} short-period superlattices by molecular beam epitaxy are investigated as a function of the global strain between the short-period superlattice and (001)InP substrate. For samples grown under tension, transmission electron and atomic force microscopy reveal composition modulations along directions close to {l_angle}310{r_angle} coupled to a surface cusping. For samples grown under compression, we observe composition modulations roughly along the elastically soft {l_angle}100{r_angle} directions coupled to a surface rippling. For high strains ({ge}0.7{percent}), with individual InAs layer thicknesses {le}1.6 monolayers, we observemore » weak or no composition modulations. {copyright} {ital 1998 American Institute of Physics.}« less
  • A high-performance short-wavelength infrared n-i-p photodiode based on InAs/InAs{sub 1−x}Sb{sub x}/AlAs{sub 1−x}Sb{sub x} type-II superlattices on GaSb substrate has been demonstrated. The device is designed to have a 50% cut-off wavelength of ∼1.8 μm at 300 K. The photodetector exhibited a room-temperature (300 K) peak responsivity of 0.47 A/W at 1.6 μm, corresponding to a quantum efficiency of 37% at zero bias under front-side illumination, without any anti-reflection coating. With an R × A of 285 Ω cm{sup 2} and a dark current density of 9.6 × 10{sup −5} A/cm{sup 2} under −50 mV applied bias at 300 K, the photodiode exhibited a specific detectivity of 6.45 × 10{sup 10 }cm Hz{supmore » 1/2}/W. At 200 K, the photodiode exhibited a dark current density of 1.3 × 10{sup −8} A/cm{sup 2} and a quantum efficiency of 36%, resulting in a detectivity of 5.66 × 10{sup 12 }cm Hz{sup 1/2}/W.« less
  • Spontaneous lateral composition modulation as a consequence of the deposition of a (AlAs){sub n}/(InAs){sub m} short period superlattice on an InP(001) substrate is examined. Transmission electron microscopy images show distinct composition modulation appearing as vertical regions of In- and Al-rich materials alternating in the [{bar 1}10] projection. The periodicity of the modulation is 130 {Angstrom}, and is asymmetric. The transmission electron and x-ray diffraction patterns from the structure exhibit distinct satellite spots which correspond to the lateral periodicity. Transmission electron microscopy images show that the individual superlattice layers possess cusplike undulations, which directly correlate with the composition modulation. Composition modulationmore » in this sample appears to be coupled to morphological and compositional instabilities at the surface due to strain. {copyright} {ital 1997 American Institute of Physics.}« less
  • Laterally modulated composition profiles in AlAs/InAs short-period superlattices grown by molecular-beam epitaxy under tensile strain on (001) InP are examined by transmission electron microscopy (TEM) and x-ray diffraction {ital K} mapping. Weak, one-dimensional modulation with a wavelength of {lambda}{sub m}=110thinsp{Angstrom} is observed for a period of 1 ML. At 2 ML, the composition profile is irregular, while a two-dimensional network of wire and dot structures with {lambda}{sub m}=130thinsp{Angstrom} occurs at 3 ML. At a high growth rate, 4-ML samples exhibit smooth modulated profiles with {lambda}{sub m}=220thinsp{Angstrom}. When the growth rate is reduced with beam interrupts, sharp profiles develop that showmore » strong alignment in the substrate plane with {lambda}{sub m}=270thinsp{Angstrom}. TEM dark-field image contrast of the modulated profiles is simulated using dynamical diffraction theory to reproduce features observed in experiment. {copyright} {ital 1998 American Institute of Physics.}« less
  • The formation of quantum wires has much interest due to their novel electronic properties which may lead to enhanced optoelectronic device performance and greater photovoltaic efficiencies. One method of forming these structures is through spontaneous lateral modulation found during the epitaxial growth of III/V alloys. In this paper, we report and summarize our investigations on the formation of lateral modulation in the molecular-beam epitaxy grown InAlAs/InP(001) system. This system was grown as a short-period superlattice where {ital n} monolayers of InAs are deposited followed by {ital m} monolayers of AlAs (with {ital n} and m{approximately}2) and this sequence is repeatedmore » to grow a low strain InAlAs ternary alloy on InP(001) that exhibits lateral modulation. Films were grown under a variety of conditions (growth temperature, effective alloy composition, superlattice period, and growth rate). These films have been extensively analyzed using x-ray diffraction, atomic force microscopy, and transmission electron microscopy (TEM) and microcharacterization, in addition to photon-based spectroscopes. Here we present results of several microstructural characterizations using a wide range of TEM-based techniques, and compare them to results from the other methods to obtain a unified understanding of composition modulation. Two strong points consistently emerge: (1) The lateral modulation wavelength is insensitive to growth temperature and effective alloy composition, but the strength of the lateral modulation is greatest near an effective alloy composition of In{sub 0.46}Al{sub 0.54}As, which corresponds to a slightly tensile global strain with respect to InP. (2) The composition variation for the strongly modulated films is as much as 0.38 InAs mole fraction. In addition, for these strongly modulated films, the modulation wave is asymmetric showing strongly peaked, narrower InAs-rich regions separated by flat AlAs-rich regions. We discuss these results and their possible implications in addition to detailing the techniques used to obtain them. {copyright} {ital 1999} {ital The American Physical Society}« less