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Lai, Shui Tong Klein, Miles V. 2011-06-27T15:08:10Z 2011-06-27T15:08:10Z 10000-01-01 1980 We have studied in detail a new structure Mx/0 in photoluminescence spectra from n-type indirect GaAs P alloys. The intensity of Mx/0 starts l -x x to saturate relative to that of the donor-bound exciton (Do) at very low excitation laser po\vcr. It has a low activation energy (2 meV) and prominant X-point phonon sidebands. Its wave function is effective-mass-like and is associated with the X-point in K-space. We interpret the MO band as due to excitons localized by the random potentials in the alloys. Lifetime measurements show that the Mx/0 excitons are relatively long lived (tens of microseconds) and it varies over the spectral regions of the M~ emission band. This can be understood in terms of the energy-dependence of the effective range of the excitons in the presence of impurity centers in the sample. Such characteristic is unique for the Anderson-type localized excitons. The valley-anisotropy (V-A) splitting of the localized exciton is directly observed under resonant excitation at Mx/0. The lineshape of the enhancement curves of a prolllinent longitudinal accoustic phonon (LAX) side- band of Mx/0 changes with temperature. This provides information which is necessary for the identification of the V-A split excited state. The pseudo-extended nature of the excited state plays an important role in the low activation energy of Mx/0. The asymmetric lineshape of Mx/0 is qualitatively explained. Submitted by Carolyn Mead (cmead2@illinois.edu) on 2011-06-27T15:08:10Z No. of bitstreams: 1 1980_lai.pdf: 3281376 bytes, checksum: 80cdd3e04e3c8f81e5e43a7436521bc7 (MD5) Made available in DSpace on 2011-06-27T15:08:10Z (GMT). No. of bitstreams: 1 1980_lai.pdf: 3281376 bytes, checksum: 80cdd3e04e3c8f81e5e43a7436521bc7 (MD5) Previous issue date: 1980 Restriction data tranferred 2014-07-01T11:32:23-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: Thesis Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Mead (cmead2@illinois.edu) on 2011-06-27T15:08:10Z Item is restricted indefinitely. Thesis U of I Only 452695 http://hdl.handle.net/2142/25530 en 1980 Shui Tong Lai exciton random potential indirect gallium arsenide phosphide alloys photoluminescence Study of exciton localized by random potential in indirect gallium arsenide phosphide alloys Dissertation / Thesis text Physics Physics University of Illinois at Urbana-Champaign Dissertation Ph.D.