Impurity Vibrational Properties of Ga in InP Crystals

Abstract

b), a n d V . V . T o~o~o v (b) A theoretical and experimental study is undertaken on the vibrational mode frequencies, infrared and Raman response functions of isolated substitutional Ga impurities in InP. The calculations are based on the existing rigid-ion and defect models for isolated impurities in zincblende lattices. They yield an impurity-induced infrared absorption and Raman scattering in the regions a few cm-1 above the maximum TA, LA, and optical phonon frequencies. Experimentally the infrared reflection and Raman scattering are measured of InP containing 1% Ga impurities. A local mode is observed 4.5 cm-I above the LO(I') frequency of InP. From these experimental data the relative force constant change around the Ga impurity is estimated to Af/f u 0.14. Die Schwingungsfrequenzen, Infrarot-und Raman-Responsefunktionen von InP mit Ga alsSubstitutionsstorstelle werden theoretisch und experimentell untersucht. Die Rechnungen basieren auf dem bereits bekannten Modell starrer Ionen und dem ebenfalls bekannten Defektmodeli fur isolierte Storstellen in Zinkblendegittern. Sie liefern eine storstelleninduzierte Infrarotabsorption und Ramanstreuung in den Bereichen wenige cm-l oberhalb der maximalen TA-, LAund optischen Phononfrequenzen von InP. Experimentell wird die Infrarotreflexion und Ramanstreuung von I n P mit 1% Ga gemessen und dabei eine Lokalmode 4,5 cm-l oberhalb der LO(T)-Frequenz Ton I n P beobachtet. Daraus wird die relative Kraftkonstantenanderung bei der Substitution von Ga zu Aflf = 0,14 abgeschatzt.

Comportement à deux modes de Ga(x)In(1 - x)P ? Diffusion Raman résonnante par les modes rendus actifs par le désordre

“…Les modes de grandes longueurs d'onde ont été très étudiés dans Ga(x)In(1 -x)P [2][3][4][5]. L'ensemble des résultats à 300 K est reporté sur la figure 1. Toutes les courbes de réflectivité infrarouge font apparaître, en plus de la bande principale un pic, ou un épaulement, supplémentaire dans tout le domaine de concentration.…”

Self‐Consistent Field Approximation for the Vibrational Spectra of Quaternary Alloys

“…It is seen that the experimentally observed mode changing is qualitatively reproduced by the theory. There are some discrepancies between the theoretical and experimental frequency positions of the GaP branch, which are due to the considerable force constant change necessary to obtain the measured local mode position of Ga impurities in I n P [20]. I n view of the simplicity of our lattice dynamical model and the neglect of force constant change there is a satisfactory agreement between theory and experiment.…”

“…The mass matrix $(co2) encloses a given configuration within the cluster over which one averages in(20). I n comparison with the Cluster density of states for a mixed quaternary chain Ga,Inl-zP1 -gAs, with y = 0.6 and 2 = yI2.1, determined by an eight atom cluster embedded in the effective medium.…”

CoherentPotential Approximation for the Lattice Vibrations of Mixed III–V Crystals

“…It must be noted that the eigenvectors for x = 1 explicitly enter the set of selfconsistent equations (5) to (8).…”

“…TO solve (5) to (8) for u one has to sum over k in (6). Most numerical work is necessary to carry out this Brillouin-zone integration.…”