Band-gap evolution, hybridization, and thermal stability of InxGa1-xN alloys measured by soft X-ray emission and absorption

Philip Ryan, Cormac McGuinness, James E. Downes, Kevin E. Smith*, Dharanipal Doppalapudi, Theodore D. Moustakas

*Corresponding author for this work

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The electronic structure of InxGa1-xN alloys with (0≤x≤0.3) has been studied using synchrotron radiation excited soft x-ray emission and absorption spectroscopies. These spectroscopies allow the elementally resolved partial density of states of the valence and conduction bands to be measured. The x-ray absorption spectra indicate that the conduction band broadens considerably with increasing indium incorporation. The evolution of the band gap as a function of indium content derives primarily from this broadening of the conduction-band states. The emission spectra indicate that motion of the valence band makes a smaller contribution to the evolution of the band gap. This gap evolution differs from previous studies on the AlxGa1-xN alloy system, which observed a linear valence-band shift through the series (0≤x≤1). For InxGa1-xN the valence band exhibits a large shift between x=0 and x=0.1 with minimal movement thereafter. We also report evidence of In 4d-N 2p and Ga 3d-N 2p hybridization. Finally, the thermal stability of an In0.11Ga0.89N film was investigated. Both emission and absorption spectra were found to have a temperature-dependent shift in energy, but the overall definition of the spectra was unaltered even at annealing temperatures well beyond the growth temperature of the film.

Original languageEnglish
Article number205201
Number of pages7
JournalPhysical Review B: Condensed Matter and Materials Physics
Volume65
Issue number20
DOIs
Publication statusPublished - 24 Apr 2002
Externally publishedYes

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