HP Labs Technical Reports
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Photoluminescence Excitation Spectroscopy Yields Bandgap of Ga(sub.5) In(sub.5)P Containing Relatively Ordered Domains
Fouquet, Julie E.; Minsky, Milan; Rosner, S. Jeff
Abstract: Photoluminescence excitation spectroscopy at 9 K reveals that the absorption edge of Ga.5In.5P containing relatively ordered domains (grown at 670 degree C) is near 1.93 eV, representing the bandgap of this inhomogeneous material. Photoluminescence has been observed at energies as much as 70 meV lower than this absorption edge energy. Along with our previous time-resolved photoluminescence results - which show unusually slow decay times - the low energy photoluminescence indicates spatially indirect recombination. Therefore, photoluminescence alone can not reliably determine the bandgap of typical "ordered" Ga.5In.5P samples. In contrast, photoluminescence of relatively randomly-ordered ("normal") Ga.5In.5P (grown at 775 degrees C) occurs at the same energy as the absorption edge and exhibits a rapid decay time. These characteristics are typical of a normal direct III-V semiconductor.
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