ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Hexagonal AlN, epitaxially grown on GaAs, is studied using x-ray absorption measurements at the N-, O-, and Al-K edges. The measured distances of the nitrogen nearest neighbors (nn) are found shorter than expected by 0.04–0.13 Å for the first to third nn shells, respectively. Nitrogen atoms are fourfold coordinated with Al as first nearest neighbors (nn), while Al atoms are fourfold coordinated with N and O atoms. The Al–N distance is 1.85 Å, i.e., it is smaller by 0.04 Å than expected. A reduction in the nn distances is also observed in the second and third nn shells where the N–N and the N–Al distances are found 0.07 and 0.13 Å shorter than expected, respectively. The reduction in the nn distances is attributed to the presence of oxygen contamination. The Al–O distance is only 0.18 Å smaller than the Al–N distance, i.e., O is a substitutional impurity in the N sublattice. The characteristic angular dependence of the N-K edge NEXAFS spectra verifies the hexagonal structure of the AlN film. Moreover, from the dependence of the areas under the NEXAFS resonances versus the angle of incidence cursive-theta, the directions of maximum electron charge densities are determined. Finally, the p-partial density of states in the conduction band is discussed. © 1997 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.365884
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