Investigation On The Optical Properties Of GaPN Alloy And The Transient Photoluminescence Of GaInP And AlGaInP Alloys

III-V semiconductors are important candidate materials for optoelectronic devices. In this work of part 1, as a main body of this dissertation, multiple experimental methods are applied to investigate the optical properties of GaP1-xNx alloys with the N composition varying from 0.05% to 3.1%. In part 2, the transient photoluminescence of III-V semiconductor GaInP and AlGaInP alloys are studied.In chapter 1, the history investigation of GaP:N with dilute nitrogen concentration, especially its isoelectronic exciton mechanics and the study background of GaPN alloys are briefly introduced. The isoelectronic system of GaP:N has been investigated extensively in the dilute limit since 1965. Thomas et al identified that a series of sharp emission lines in GaP:N were due to the recombinations of excitons bound to either isolated nitrogen centers or various nitrogen pair centers. Recently many attentions have been paid to the study of nitride-related compounds due to their potential application in short-wavelength optical devices, such as blue light emitting diodes(LEDs) and violet laser diodes. Hence, the heavily doped nitrogen in GaP, usually called GaPN alloy, becomes an interesting system. However, it is not easy to incorporate large N concentration in GaP due to the large differences in lattice structure (GaN belongs to wurtzite structure while GaP zinc blende structure) and in lattice constant (~20%) between GaN and GaP, which will lead to an extremely large miscibility gap. Fortunately, with the improvement in the material growth, GaP1-xNx alloys with nitrogen concentration as high as several percentage have been successfully grown by molecular beam epitaxy (MBE) or metalorganic vapor-phase epitaxy (MOVPE). More and more attentions have been paid to this alloy for its distinct property such as the giant band gap and effect, for this reason, GaP1-xNx alloys are usually called abnormal alloys.In part 2, The photoluminescence evolution of GaP1-xNx alloys with various x compositions have been investigated. At low x composition, the emission spectra exhibitsharp lines of excitons recombination and their phonon sidebands bound to different centers. With increasing x, the intensities of the deep NNi centers and their phonon sidebands become enhanced and their PL linewidths gradually broaden and shift to lower energies. Such phenomenon suggests that an intercenter interaction is taken place. When x is above 1.3%, the emission spectra are strongly broadened and do not show any well-defined features, and their peak positions shift to lower energies correspondingly with increasing x. The large band-gap bowing of GaP1-xNx alloy is induced by the impurity band formation due to the intercenter interaction. At the same time, We show that under a proper nitrogen doping concentration, due to the "concentration quenching" effect, the full spectrum of the NN3 center (i.e., its zero phonon line and various phonon replicas) is revealed without the interference from the spectra of other higher energy centers (especially NN4-NN6). The investigation of the exciton-phonon coupling of NN3 center offers a direct proof that all the phonon replicas are the phonon sidebands governed by the Huang-Rhys' multiphonon optical transition theory, and clarifies the speculations that the replicas associated with optical phonons are independent bound states of exciton-phonon complexes or due to other alternative mechanisms. Also, the different temperature dependence between the sidebands of NNi and the zero phonon line indicates there might exist other N impurity states.In chapter 3, The Raman scattering of GaP1-xNx alloys have been studied at room temperature. In addition to the strong GaP-like LO1 mode and weak forbidden TO1 mode, the second order Raman scattering of the Brillouin zone-edge phonon (2LO1(L) mode and 2TO1(X) mode) as well as the scattering of the Brillouin zone-center phonon were observed. Also, the nitrogen local mode (495 cm-1) associated with the NN center and the so-called "X" mode (387 cm-1) of the LO phonon (manifest...