Photoreflectance (PR), Raman scatter (RS), and photoluminescence (PL) experiments have been carried out to characterize the In0.52Al0.48As surface exposed to plasma with a gas of methane-hydrogen. PR spectra indicate that reactive ion etching (RIE) causes damage such as nonradiative recombination centers, scattering centers, and defects leading to the decrease of signal intensity, broaden linewidth and red shift of the transitions by increasing the rf power. In the Raman scattering study, RIE causes damage against InAs-like and AlAs-like longitudinal optic (LO) modes vibration. As the rf power increased, the maximum of two LO modes shifts towards lower frequency and the line shape becomes increasingly asymmetric. Also, the degraded intensity causes by disorder and point defects gradually with increasing rf power. Corresponding PL measurements showed that the transition energies red-shift with increasing the rf power. In addition, the spectral feature a broadens, and the intensity decreases with rf power more than 200 W. There is a good correlation of the PL, PR, and RS indicating that these methods can be used as sensitive evaluate for near surface damage of the epilayer.

Photoluminescence and Raman spectroscopies are employed to study undoped InGaP layers grown on GaAs (100) substrates at 750 °C by liquid phase epitaxy. There are four peaks in the photoluminescence spectrum in the energy range between 1.55 and 2.25 eV. Besides a bound exciton recombination, three longitudinal optical phonon replicas with one superimposed donor-acceptor emission are identified based upon their dependences of emission energies on temperature and excitation intensity.

The incorporation of prascodymiiim (Pr) into GaAs, Ino,s:,Ga,,.d.rAs, and InP during liquid-phase epitaxy were investigated by double crystal x-ray diffraction, Hall effect, low tcmperature photoluniiricscerice (PL) measnrements. The lattice mismatch slightly vary with Pr concentration in the growth mclts. Examinations of the electrical property illustrate that the lower carriers conccntrations and a higher mobilities are obtain from Pr-doped epilayers than undopcd sample (In~,.~:~Gq~.~i.As and InP). The PL spcctra (15-K) show that thc intensity of the impurity related peaks decreases and the mar-hand-to-hand luminescence intensity increase. They also reveal that the irnpuritics are gettered by Pr ions during LPE growth. Thus, for the purpose of purification, propcr amonrit of Pr in the growth melts is suggested. No intra-4f-shell transition line is observed from the Pr-doped GaAs, In,).s:{Ga,,,47As, and InP layers.

We have performed Photoreflectance (PR), Raman Scattering (RS), and Photoluminescence (PL) experiments to characterize the Ino.52Alo.48As surface exposed to plasma by a gas mixture of CHJHz/Ar, PR spectra indicate that RIE (plasma) causes defects such as nonradiative recombination centers, scattering centers, and defects leading to the decrease of signal intensity, broaden line width and red shift of the transitions by increasing the rf power. In the Raman scattering study, RIE causes defects against InAs-like and AIAs-like LO modes vibration. As the rf power increased, the maximum of two LO modes shifts towards lower frequency and the line shape becomes increasingly asymmetric. Also, the intensity degrades gradually by disorder and point defects with increasing rf power. The PL transition energies show a red-shift with increasing the rf power. In addition, the spectral feature broadens, and the intensity decreases with rf power higher than 200 w. The consistence of the PL, PR, and RS results indicate that these three methods can be used as sensitive probes to evaluate the near surface damage of the epilayer.

Photoluminescence measurement is used to characterize the sulfur-doped GaAs epitaxial layers grown on GaAs(100) substrates by liquid phase epitaxy. The dependences of spectral line shape on the doping levels ranged from 5×1017 to 1.8×1018 cm-3 as functions of excitation power and temperature have been investigated. Three main competing near-band-edge radiative transitions are identified as: direct conduction band to valence band transition, conduction band filling levels to valence band tail transition, and donor-related states to valence band tail or to acceptor transition. In order to explain the spectral shifting and broadening observed in heavily sulfur-doped GaAs, the luminescence peak emitted from the conduction band filling to valence band tail transition is also compared with theoretical calculations where the carrier concentration dependence of peak energy can be well described based on the heavy doping induced band-tail effect.