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HL: Halbleiterphysik
HL 25: GaN I
HL 25.7: Talk
Thursday, March 20, 1997, 11:45–12:00, H1
N-K-edge EXAFS Study of Epitaxial GaN Films — •M. Katsikini1, E.C. Paloura1, M. Fieber-Erdmann2, T.D. Moustakas3, H. Amano4, and I. Akasaki4 — 1Aristotle Univ., Dept. of Physics, GR-54006 Thessaloniki — 2Hahn-Meitner-Institut, AG AS, D-14109 Berlin — 3Boston Univ., Dep. of Elec., MA 02215 Boston, USA — 4Meijo Univ., Dep. of Elec. and Elec. Eng., 468 Nagoya, Japan
X-ray absorption measurements at the N-K edge are used to study the local microstructure in cubic and hexagonal GaN films grown by ECR-MBE and MOVPE on p-Si(100) and Al2O3, respectively. The EXAFS measurements were conducted in the fluorescence detection mode at room- and low temperatures using a high purity Ge detector at BESSY, BERLIN. A distortion in the local microstructure is identified in the 1st and 3rd nearest neigbor (nn) shells consisting of Ga atoms in both the cubic and the hexagonal samples. In the cubic sample, 2 Ga atoms are found at the expected distance of 1.96Å from the absorbing N atom while the other two Ga atoms are displaced by about 0.25Å. The same distortion is detected in the 3rd nn shell where 8 of Ga atoms are at the expected distance of 3.69Å while 4 atoms are at 4.05Å. The nitrogen 2nd nearest neigbor is found at the expected distance of 3.12Å. The results are discussed in view of the stress and previously reported distortions in compounds containing tetrahedrally bonded nitrogen [1].
[1] S. Jin and T. Moustakas, Appl. Phys. Lett. 65, p. 403 (1994)