TY - JOUR
T1 - High temperature growth of AlN by plasma-enhanced molecular beam epitaxy
AU - Fan, Z. Y.
AU - Rong, G.
AU - Browning, J.
AU - Newman, N.
N1 - Funding Information:
The authors thank Mr. Adrian Lee for his help to set up the experiment system, and Dr. Colin Wood for his encouragement and support. This work was supported by the Office of Naval Research (Contract No. N00014-96-1-1002).
PY - 1999/12/8
Y1 - 1999/12/8
N2 - AlN(0001) films have been grown by plasma-enhanced molecular beam epitaxy on sapphire(0001) surfaces utilizing monoenergetic activated-nitrogen beams at elevated substrate temperatures (900-1300 °C). AlN films synthesized under stoichiometric conditions, with ECR microwave powers of less than 100 W, substrate temperatures of 925-1150 °C and a low temperature buffer layer exhibit narrow X-ray diffraction rocking curve widths [6 arcmin, AlN(0002)]. Smooth surface morphologies with typical RMS surface roughness of approximately 15 angstroms are found for approximately 1 μm AlN growth when the lower range of substrate temperatures are used. The φ-scan of the AlN(101̄3) X-ray Bragg reflection has six-fold symmetry with peak widths of 1.6°, indicating that the highest quality films are aligned, albeit with small angle grain boundaries in the a-b plane. Lattice constants of 3.079 angstroms (a) and 5.036 angstroms (c) are inferred from the X-ray diffraction data, indicating a bi-axial compressive strain of 1.03% in the a-b plane. Even smoother surfaces with an RMS roughness approximately 6 angstroms can be produced if pre-growth surface nitridation is eliminated. In that case, degradation in the AlN thin-film crystal quality is found, as judged by the 24 arcmin rocking curve widths. The influence of growth conditions (i.e. substrate temperature, ratio of activated-nitrogen to Al flux, ion kinetic energy, pre-growth sapphire nitridation and the properties of the buffer layer) on the resulting crystal quality and surface morphology are directly addressed.
AB - AlN(0001) films have been grown by plasma-enhanced molecular beam epitaxy on sapphire(0001) surfaces utilizing monoenergetic activated-nitrogen beams at elevated substrate temperatures (900-1300 °C). AlN films synthesized under stoichiometric conditions, with ECR microwave powers of less than 100 W, substrate temperatures of 925-1150 °C and a low temperature buffer layer exhibit narrow X-ray diffraction rocking curve widths [6 arcmin, AlN(0002)]. Smooth surface morphologies with typical RMS surface roughness of approximately 15 angstroms are found for approximately 1 μm AlN growth when the lower range of substrate temperatures are used. The φ-scan of the AlN(101̄3) X-ray Bragg reflection has six-fold symmetry with peak widths of 1.6°, indicating that the highest quality films are aligned, albeit with small angle grain boundaries in the a-b plane. Lattice constants of 3.079 angstroms (a) and 5.036 angstroms (c) are inferred from the X-ray diffraction data, indicating a bi-axial compressive strain of 1.03% in the a-b plane. Even smoother surfaces with an RMS roughness approximately 6 angstroms can be produced if pre-growth surface nitridation is eliminated. In that case, degradation in the AlN thin-film crystal quality is found, as judged by the 24 arcmin rocking curve widths. The influence of growth conditions (i.e. substrate temperature, ratio of activated-nitrogen to Al flux, ion kinetic energy, pre-growth sapphire nitridation and the properties of the buffer layer) on the resulting crystal quality and surface morphology are directly addressed.
UR - http://www.scopus.com/inward/record.url?scp=0033285395&partnerID=8YFLogxK
U2 - 10.1016/S0921-5107(99)00213-5
DO - 10.1016/S0921-5107(99)00213-5
M3 - Conference article
AN - SCOPUS:0033285395
SN - 0921-5107
VL - 67
SP - 80
EP - 87
JO - Materials Science and Engineering B: Solid-State Materials for Advanced Technology
JF - Materials Science and Engineering B: Solid-State Materials for Advanced Technology
IS - 1
T2 - Proceedings of the 1999 1st Lawrence Symposium on Critical Issues in Epitaxy
Y2 - 6 January 1999 through 9 January 1999
ER -