Lattice parameters, deviations from Vegard’s rule, and E2 phonons in InAlN

Abstract

Published by the AIP PublishingArticles you may be interested in Raman spectra investigation of InAlGaN quaternary alloys grown by metalorganic chemical vapor deposition

Elastic constants, composition, and piezolectric polarization in InxAl1−xN: Fromab initiocalculations to experimental implications for the applicability of Vegard's rule

“…3 and Table II that the lattice parameters of In x Al 1−x N show very small deviations from linearity, δ a = 0.0412 ± 0.0039Å and δ c = −0.060 ± 0.010Å. 17 C 11 , C 44 , and B exhibit larger deviations from Vegard's rule with δ C 11 = 98.6 GPa, δ C 44 = 47.3 GPa, and δ B = 71.3 GPa, while C 13 , C 13 , and C 13 exhibit essentially linear dependences with composition (Table II and Apart from the (1013), the rest of the planes show significant bowing parameters of the biaxial coefficients. Our GGA stiffness constants (Table II) are somewhat lower than recent results obtained using LDA calculations based on 32-atom supercell.…”

“…Recently, we have shown by ab initio calculations that the In x Al 1−x N lattice parameters slightly deviate from Vegard's rule. 17 Although small, these deviations are important to account for in order to determine the alloy composition correctly. In addition, in order to extract alloy composition from XRD measurements, the strain should be considered and therefore the stiffness constants of the In x Al 1−x N alloy need to be known.…”

“…For instance, the compositional dependencies of the band gap bowing parameters, [11][12][13] lattice parameters, and applicability of Vegard's rule to the lattice parameters are debated. [14][15][16][17] The alloy stiffness constants and strain effects on many of the fundamental properties are still not conclusively established. [18][19][20] Furthermore, the precise control of In x Al 1−x N alloy composition, which is mandatory for device design and fabrication, remains an issue.…”

Effect of Mg doping on the structural and free-charge carrier properties of InN films

“…Mg occupies the In site in the crystal lattice of InN doped with Mg. 5 We have shown very recently by first principle calculations that the incorporation of Mg leads to decrease of c and a lattice parameters as a result of the size effect with 67 68 and the resulting lattice mismatch will also cause compressive in-plane strain. Therefore, the biaxial strain component cannot lead to the observed increase in the a-lattice parameter of InN either.…”

Measurement of probability distributions for internal stresses in dislocated crystals

“…The In content was slightly different for the two samples (17.6% on the sapphire compared to 21.4% on the SiC). The Burgers vector and elastic constants used in the analysis were altered slightly according to the corrected Vegard's law to account for changes in lattice parameters and elastic constants given by Darakchieva et al 22 Electron channelling contrast imaging observations on these samples have previously reported dislocation densities of 2.4 Â 10 9 cm À2 and 1.4 Â 10 9 cm À2 for the films on sapphire and SiC, respectively. 13 Of these, only a small fraction ($10% for sapphire, $1% for SiC) were observed to be screw hci type which would not contribute to the r 12 shear stress analysed here while the remaining edge hai type and mixed hc1ai type dislocations contribute equally to r 12 .…”