Localized exciton-phonon complex as an intermediate state in light scattering

A $\text{sharp}$ LO-phonon replica of the first order Raman spectrum of (Ga_xIn_1-xP and Ga(As_1-xP_x) has been observed for the first time. The experiment shows strong resonance with varying incoming photon energy which only appears in the presence of alloying and disorder. The results can only be understood if the relevant resonant intermediate state is a localized sharp exciton strongly interacting with the LO-phonon system, i.e. a localized exciton-phonon complex. Under those conditions, a simple model yields a ratio of the two-phonon to one-phonon intensities which is given by straightforward Franck-Condon overlaps.     

Spin-flip Raman scattering in CdS and High resolution spectroscopy near 5145 Å

Spin-flip Raman scattering is observed in CdS, from electrons bound to donors, using the 5145 Å line of an argon-ion laser. A high improvement is provided by the use of an iodine vapour cell in the scattered beam to filter the stray light at excitation frequency. Using the spin-flip line as a magnetically tuneable source a high resolution absorption spectrum is obtained for I₂, near 5145 Å. A technique is suggested to improve the accuracy in the determination of the g factor, and to measure low g values and g-factor anisotropies.     

Alloy contribution to phonon softening in ultra-heavily doped Si:As

Experimentally observed phonon softening of the 520 cm^-1 Raman line in ultra-heavily doped n-Si is attributed to the electron-phonon self-energy effects as well as change in lattice force constants of the alloy system.     

GaP:N和GaAs1-xPx:中的束缚激子依赖于激子声子耦合的辐射复合的热猝灭

我们从实验中发现,在N掺杂的GaP和Ga(As,P)中,零声子辐射带与相应的声子伴带的热猝灭过程是不同的。声子伴带的热猝灭强烈地依赖于激子声子的耦合,呈现出一种相干的特性。     

Line-shapes of localized impurity phonon modes of boron acceptors in silicon

The Raman scattering cross-section of localized phonon modes due to impurities has been measured. Interference effects between the localized phonon and electronic continuum scattering amplitudes are signalled by the onset line-shape asymmetries. Qualitative analysis of the results is given in terms of the Fano theory.     

Electron-phonon interaction in Raman scattering of Li-doped ZnTe

Raman scattering has been measured at low temperatures on Li doped ZnTe, using Kr and dye lasers. Besides the usual phonon spectrum, electronic transitions between acceptor bound states 1S→2S (A band), 1S→3S, 1S→4S, are observed. A peak located between the TO and LO bands is interpreted in terms of a bound LO-phonon mode related to the p acceptor states. The sidebands of the A band, at one and two LO-phonons are observed as well, whose energies are found to be respectively 12 and 26 cm^?1 smaller than the expected values. A simple self-energy model is invoked to explain the energy shift due to electron-phonon interaction.     

Raman scattering study of glass crystallization kinetics

Laser induced glass-crystalline transition is studied by light scattering. Three significant effects are observed depending on the incident laser energy density: (i) Spectral band narrowing indicating cluster enlargement constitutes a precursor effect, (ii) an intensity increase effect indicates a rapid rise of the density of clusters attaining microcrystalline size and (iii) a dynamical reversal effect indicative of glass-crystalline instability. Cluster volume and crystallization appear as separate but related threshold phenomena.     

Optical constants and band gap of PbTe from thin film studies between 25 and 300°K

Optical constants of PbTe have been derived in the fundamental gap region between 25 and 300°K. It is shown in this paper by a direct compatibility check through Kramers-Krönig inversion, that properly prepared thin films have the optical properties of homogeneous material. A physical model is used to relate the optical edge and the refractive index signularity to the band gap and a value of the low-temperature dispersion of the refractive index is given, for the low-energy side of the singularity where photoelectronic phenomena take place. The precise shape of the refractive index singularity, and its relation to band tailing are discussed. The values of the optical band-gap temperature coefficient are compared with results from other authors.