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HL: Halbleiterphysik
HL 40: Poster III
HL 40.83: Poster
Friday, March 21, 1997, 11:00–14:00, Z
Determination of the Existance and Percentage of Cubic and Hexagonal Phases in GaN Using NEXAFS — •M. Katsikini1, E.C. Paloura2, T.D. Moustakas3, E. Holub-Krappe1, and J. Antonopoulos2 — 1Hahn-Meitner-Institut, AG AS, Glienickerstr. 100, D-14109 Berlin — 2Aristotle Univ. of Thessaloniki, Dept. of Physics, GR-54006 Thessaloniki, Greece — 3Boston Univ., Dep. of Elec., 44 Cummington st., MA 02215 Boston, USA
Angle resolved near edge X-ray absorption measurements (NEXAFS) are used to access the presence and concentration of the two allotropic phases (cubic and hexagonal) in mixed GaN samples grown by ECR-MBE. The NEXAFS measurements were conducted at the N-K-edge in the fluorescence detection mode at BESSY. The intensities of the individual resonant lines in the NESAFS spectra are independent of the angle of incidence θ (grazing and normal incedence) for cubic material. In contrary for the hexagonal material this dependance is evident. Based on the energy positions of the NEXAFS resonances a method is proposed to determine: (1) Whether the material is pure hexagonal and/or cubic and (2) The percentage of the allotropic phases in the mixed sample. Application of the method to a mixed phase sample yields results which are in very good agreement with previously reported XTEM and XRD results. From the characteristic angular dependence of the intensities of the NEXAFS resonances in the hexagonal material (I=A-Bcos2(θ)) the bond orientation is determined.