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

Title: Deviations from Vegard's rule in Al{sub 1-x}In{sub x}N (0001) alloy thin films grown by magnetron sputter epitaxy

Abstract

Al{sub 1-x}In{sub x}N (0001) thin films of the pseudobinary AlN-InN system were grown epitaxially onto (111)-oriented MgO wafers with seed layers of Ti{sub 1-y}Zr{sub y}N by dual direct current magnetron sputtering under ultrahigh vacuum conditions. The relaxed film c-axis lattice parameters determined by x-ray diffraction were studied as a function of composition in the range of 0.07<x<0.82 measured by Rutherford backscattering spectrometry. We find a relative deviation by as much as 37% from the linear dependency described by Vegard's rule for the lattice parameter versus film composition. The highest relative deviations were found at low InN mole fractions, while the largest absolute deviation was found at x=0.63. This shows that Vegard's rule is not directly applicable to determine the compositions in the wurtzite Al{sub 1-x}In{sub x}N system.

Authors:
; ; ; ;  [1];  [2]
  1. Thin Film Physics Division, Department of Physics, Chemistry, and Biology (IFM), Linkoeping University, SE-581 83 Linkoeping (Sweden)
  2. (FWI), Forschungszentrum Rossendorf e.V. (FZR), P.O. Box 510119-01314 Dresden (Germany)
Publication Date:
OSTI Identifier:
20982703
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 4; Other Information: DOI: 10.1063/1.2450675; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM ALLOYS; ALUMINIUM NITRIDES; CRYSTAL GROWTH; DEPOSITION; DIRECT CURRENT; EPITAXY; INDIUM ALLOYS; INDIUM NITRIDES; LATTICE PARAMETERS; LAYERS; MAGNESIUM OXIDES; SPUTTERING; THIN FILMS; X-RAY DIFFRACTION

Citation Formats

Seppaenen, T., Hultman, L., Birch, J., Beckers, M., Kreissig, U., and Institute for Ion Beam Physics and Materials Science. Deviations from Vegard's rule in Al{sub 1-x}In{sub x}N (0001) alloy thin films grown by magnetron sputter epitaxy. United States: N. p., 2007. Web. doi:10.1063/1.2450675.
Seppaenen, T., Hultman, L., Birch, J., Beckers, M., Kreissig, U., & Institute for Ion Beam Physics and Materials Science. Deviations from Vegard's rule in Al{sub 1-x}In{sub x}N (0001) alloy thin films grown by magnetron sputter epitaxy. United States. doi:10.1063/1.2450675.
Seppaenen, T., Hultman, L., Birch, J., Beckers, M., Kreissig, U., and Institute for Ion Beam Physics and Materials Science. Thu . "Deviations from Vegard's rule in Al{sub 1-x}In{sub x}N (0001) alloy thin films grown by magnetron sputter epitaxy". United States. doi:10.1063/1.2450675.
@article{osti_20982703,
title = {Deviations from Vegard's rule in Al{sub 1-x}In{sub x}N (0001) alloy thin films grown by magnetron sputter epitaxy},
author = {Seppaenen, T. and Hultman, L. and Birch, J. and Beckers, M. and Kreissig, U. and Institute for Ion Beam Physics and Materials Science},
abstractNote = {Al{sub 1-x}In{sub x}N (0001) thin films of the pseudobinary AlN-InN system were grown epitaxially onto (111)-oriented MgO wafers with seed layers of Ti{sub 1-y}Zr{sub y}N by dual direct current magnetron sputtering under ultrahigh vacuum conditions. The relaxed film c-axis lattice parameters determined by x-ray diffraction were studied as a function of composition in the range of 0.07<x<0.82 measured by Rutherford backscattering spectrometry. We find a relative deviation by as much as 37% from the linear dependency described by Vegard's rule for the lattice parameter versus film composition. The highest relative deviations were found at low InN mole fractions, while the largest absolute deviation was found at x=0.63. This shows that Vegard's rule is not directly applicable to determine the compositions in the wurtzite Al{sub 1-x}In{sub x}N system.},
doi = {10.1063/1.2450675},
journal = {Journal of Applied Physics},
number = 4,
volume = 101,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • Single-crystal Al{sub 0.8}In{sub 0.2}N(0001) thin films were grown epitaxially onto lattice-matched Ti{sub 0.2}Zr{sub 0.8}N(111) seed layers on MgO(111) substrates at 300 deg. C by magnetron sputter epitaxy. Low-energy ion-assisted epitaxial growth conditions were achieved by applying a substrate potential of -15 V. Cross-sectional high-resolution electron microscopy verified the epitaxy and high-resolution x-ray diffraction {omega}-rocking scans of the Al{sub 0.8}In{sub 0.2}N 0002 peak (full width at half maximum {approx}2400 arc sec) indicated a high structural quality of the films. Cathodoluminescence measurements performed in a scanning electron microscope at 5 K revealed Al{sub 0.8}In{sub 0.2}N luminescence at 248 nm, or equivalently 5.0more » eV, showing that Al{sub 0.8}In{sub 0.2}N is a promising material for deep-ultraviolet optoelectronic devices.« less
  • AlN(0001) was alloyed with ScN with molar fractions up to {approx}22%, while retaining a single-crystal wurtzite (w-) structure and with lattice parameters matching calculated values. Material synthesis was realized by magnetron sputter epitaxy of thin films starting from optimal conditions for the formation of w-AlN onto lattice-matched w-AlN seed layers on Al{sub 2}O{sub 3}(0001) and MgO(111) substrates. Films with ScN contents between 23% and {approx}50% exhibit phase separation into nanocrystalline ScN and AlN, while ScN-rich growth conditions yield a transformation to rocksalt structure Sc{sub 1-x}Al{sub x}N(111) films. The experimental results are analyzed with ion beam analysis, x-ray diffraction, and transmissionmore » electron microscopy, together with ab initio calculations of mixing enthalpies and lattice parameters of solid solutions in wurtzite, rocksalt, and layered hexagonal phases.« less
  • Reactive magnetron sputter epitaxy was used to deposit thin solid films of Sc{sub 1-x}Al{sub x}N (0<=x<=1) onto MgO(111) substrates with ScN(111) seed layers. Stoichiometric films were deposited from elemental Sc and Al targets at substrate temperatures of 600 deg. C. The films were analyzed by Rutherford backscattering spectroscopy, elastic recoil detection analysis, x-ray diffraction, and transmission electron microscopy. Results show that rocksalt structure (c)-Sc{sub 1-x}Al{sub x}N solid solutions with AlN molar fractions up to approx60% can be synthesized. For higher AlN contents, the system phase separates into c- and wurtzite structure (w)-Sc{sub 1-x}Al{sub x}N domains. The w-domains are present inmore » three different orientations relative to the seed layer, namely, Sc{sub 1-x}Al{sub x}N(0001)||ScN(111) with Sc{sub 1-x}Al{sub x}N[1210]||ScN[110], Sc{sub 1-x}Al{sub x}N(1011)||ScN(111) with Sc{sub 1-x}Al{sub x}N[1210]||ScN[110], and Sc{sub 1-x}Al{sub x}N(1011)||ScN(113). The results are compared to first-principles density functional theory calculations for the mixing enthalpies of c-, w-, and zinc blende Sc{sub 0.50}Al{sub 0.50}N solid solutions, yielding metastability with respect to phase separation for all temperatures below the melting points of AlN and ScN.« less
  • Ternary wurtzite Al{sub 1-x}In{sub x}N thin films with compositions throughout the miscibility gap have been grown onto seed layers of TiN and ZrN by magnetron sputter epitaxy (MSE) using dual reactive direct current magnetron sputter deposition under ultra high vacuum conditions. The film compositions were calculated using Vegard's law from lattice parameters determined by x-ray diffraction (XRD). XRD showed that single-phase Al{sub 1-x}In{sub x}N alloy films in the wurtzite structure with [0.10<x<0.90] could be obtained at substrate temperatures up to 600 deg. C by heteroepitaxial growth. Epitaxial growth at 600 deg. C gave the crystallographic relations Al{sub 1-x}In{sub x}N(0001)//TiN,ZrN(111) andmore » Al{sub 1-x}In{sub x}N<10-10>//TiN,ZrN<110>. At higher substrate temperatures almost pure AlN was formed. The microstructure of the films was also investigated by high-resolution electron microscopy. A columnar growth mode with epitaxial column widths from 10 to 200 nm was observed. Rocking curve full-width-at-half-maximum measurements revealed highly stressed lattices for growth onto TiN at 600 deg. C. Pseudobinary MSE growth phase field diagrams for Al{sub 1-x}In{sub x}N onto ZrN and TiN were established for substrate temperatures up to 1000 deg. C. Large regimes for single-phase solid solutions were thus identified with In being the diffusing species.« less
  • Electronic-grade GaN (0001) epilayers have been grown directly on Al{sub 2}O{sub 3} (0001) substrates by reactive direct-current-magnetron sputter epitaxy (MSE) using a liquid Ga sputtering target in an Ar/N{sub 2} atmosphere. The as-grown GaN epitaxial films exhibit low threading dislocation density on the order of {<=}10{sup 10} cm{sup -2} determined by transmission electron microscopy and modified Williamson-Hall plot. X-ray rocking curve shows narrow full-width at half maximum (FWHM) of 1054 arc sec of the 0002 reflection. A sharp 4 K photoluminescence peak at 3.474 eV with a FWHM of 6.3 meV is attributed to intrinsic GaN band edge emission. Themore » high structural and optical qualities indicate that MSE-grown GaN epilayers can be used for fabricating high-performance devices without the need of any buffer layer.« less