Virginia TechSongprakob, W.Zallen, Richard H.Liu, W. K.Bacher, K. L.2014-02-112014-02-112000-08-15Songprakob, W ; Zallen, R ; Liu, WK ; et al., Aug 15, 2000. "Infrared studies of hole-plasmon excitations in heavily-doped p-type MBE-grown GaAs : C," PHYSICAL REVIEW B 62(7): 4501-4510. DOI: 10.1103/PhysRevB.62.45010163-1829http://hdl.handle.net/10919/25382Infrared reflectivity measurements (200-5000 cm(-1)) and transmittance measurements (500-5000 cm(-1)) have been carried out on heavily-doped GaAs:C films grown by molecular-beam epitaxy. With increasing carbon concentration, a broad reflectivity minimum develops in the 1000-3000 cm(-1) region and the one-phonon band near 270 cm(-1) rides on a progressively increasing high-reflectivity background, An effective; plasmon/one-phonon dielectric function with only two free parameters (plasma frequency omega(p) and damping constant gamma) gives a good description of the main features of both the reflectivity and transmittance spectra. The dependence of omega(p)(2) on hole concentration p is linear; at p = 1.4 x 10(20) cm(-3), omega(p) is 2150 cm(-1). At each doping, the damping constant gamma is large and corresponds to an infrared hole mobility that is about half the Hall mobility. Secondary-ion mass spectroscopy and localized-vibrational-mode measurements indicate that the Hall-derived p is close to the carbon concentration and that the Hall factor is dose to unity, so that the Hall mobility provides a good estimate of actual de mobility. The observed dichotomy between the de and infrared mobilities is real, not a statistical-averaging artifact. The explanation of the small infrared mobility resides in the influence of intervalence-band absorption on the effective-plasmon damping, which operationally determines that mobility. This is revealed by a comparison of the infrared absorption results to Braunstein's low-p p-GaAs spectra and to a k.p calculation extending Kane's theory to our high dopings. For n-GaAs, which lacks infrared interband absorption, the de and infrared mobilities do not differ.application/pdfenIn Copyrightmolecular-beam epitaxyheterojunction bipolar-transistorseffectivehall factorcarbon tetrabromideoptical-absorptionraman-scatteringmodesreflectancespectrareflectivityPhysicsArticle - Refereedhttp://link.aps.org/doi/10.1103/PhysRevB.62.4501https://doi.org/10.1103/PhysRevB.62.4501