Disorder-activated infrared modes and surface depletion layer in highly Si-doped hexagonal GaN

A. Kasic, Mathias Schubert, B. Kuhn, F. Scholz, S. Einfeldt, D. Hommel

Research output: Contribution to journalArticle

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Abstract

Three infrared-active low-polar modes are reported for highly Si-doped hexagonal (α-) GaN. The 0.8-1.6 μm thick films, grown by metal organic vapor phase epitaxy or molecular beam epitaxy on (0001) sapphire substrates, were studied by infrared spectroscopic ellipsometry. For GaN epilayers with free-electron concentration N≥8×1018 cm-3 we observe, besides the usual GaN transverse-optical lattice modes and coupled longitudinal-optical phonon-plasmon modes, a band of additional modes at 567.4±2.5, 752.5±0.9, and 855.0±0.9 cm-1. We tentatively assign the first one to the disorder-activated high E2 GaN mode and the third mode to an acoustic-optical combination band, whereas the origin of the second mode remains unclear. Furthermore, the ellipsometric spectra of highly n-conductive Si-doped GaN reveal thin carrier-depleted regions at the sample surface.

Original languageEnglish (US)
Pages (from-to)3720-3724
Number of pages5
JournalJournal of Applied Physics
Volume89
Issue number7
DOIs
StatePublished - Apr 1 2001

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depletion
disorders
vapor phase epitaxy
free electrons
ellipsometry
thick films
sapphire
molecular beam epitaxy
acoustics
metals

ASJC Scopus subject areas

  • Physics and Astronomy(all)

Cite this

Disorder-activated infrared modes and surface depletion layer in highly Si-doped hexagonal GaN. / Kasic, A.; Schubert, Mathias; Kuhn, B.; Scholz, F.; Einfeldt, S.; Hommel, D.

In: Journal of Applied Physics, Vol. 89, No. 7, 01.04.2001, p. 3720-3724.

Research output: Contribution to journalArticle

Kasic, A. ; Schubert, Mathias ; Kuhn, B. ; Scholz, F. ; Einfeldt, S. ; Hommel, D. / Disorder-activated infrared modes and surface depletion layer in highly Si-doped hexagonal GaN. In: Journal of Applied Physics. 2001 ; Vol. 89, No. 7. pp. 3720-3724.
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