H. Sobotta

Infrared study of lattice and free carrier effects in p-type CuInTe2 single crystals

Abstract Infrared reflectivity spectra of p-type CuInTe2 single crystals were measured at room temperature for the polarization direction E ⊥ c and E | c in the wavenumber range from 55 to 4000 cm−1. Fits to a dielectric function including contributions from lattice oscillators and free carriers gave the first determination of the effective hole masses of m p⊥ m 0 = 0.85 and m p| m 0 = 0.66 . Two optical phonon modes were found for both polarization directions.

Vibrational properties of proton-implanted crystalline InP

Abstract Infrared transmission spectra of proton implanted crystalline InP exhibit local vibrational modes at 2197 and 2212 cm-1 which are ascribed to P—H bond vibrations. The dependence of the integrated absorption A of the bands due to the P—H bonds in proton-implanted InP and GaP on the proton dose D follows the relation A ∼ Dn with n ≈ 0.4. For GaP it is established that A is proportional to the mean damage density.

Hydrogen-induced localized vibrational mode in proton implanted ZnSe single crystals

Abstract Infrared transmission spectra of proton implanted ZnSe single crystals exhibit a localized vibrational mode at 2116 cm -1 which is ascribed to Se-H bond vibrations. The dependence of the integrated absorption A of this mode on the proton fluence D follows the relation A ∼ D n with n = 0.46. The results for ZnSe are compared with previous measurements on proton implanted III–V compounds.

Infrared optical properties of InTe

Abstract Infrared reflectivity spectra of p-type InTe single crystals were measured at room temperature for the polarization directions E ⊥ c and E | c in the wavenumber range from 55–4000 cm−1. Fits to a dielectric function including contributions from lattice oscillators and free carriers gave the first determination of the effective hole masses of m p ⊥ m o = 0.12 and m p∥ m o = 0.77 . Two optical phonon modes were found for E | c and one mode for E ⊥ c.

Hydrogen incorporation behaviour and radiation damage in proton bombarded InP single crystals

Abstract In proton bombarded InP single crystals the incorporation behaviour of different hydrogen isotopes is studied in relation to implantation induced radiation defects. Investigations of the fluence dependence (D = 1016-1018 cm−2), of the depth profile and of the annealing behaviour (T an = 300–1000 K) of hydrogen incorporation and of damage density indicate that only a small fraction of the implanted hydrogen is chemically bonded to host lattice atoms. These bonded hydrogen atoms saturate dangling bonds at defect sites.

Infrared reflectivity spectra of GaS1−xSex mixed crystals

Infrared reflectivity spectra of GaS1−xSex mixed crystals are measured for E ‖ c in the wavenumber range from 180 to 4000 cm−1. Two-mode behaviour is found for the infrared active optical modes. The composition dependence of the mode frequencies can be described by the MREI model if a nonlinear change of the force constants with composition is assumed.

Infrared lattice vibration spectra of tetragonal ZnP2

Abstract Infrared reflectivity spectra of tetragonal ZnP2 are measured in the frequency range from 40 to 600 cm-1 for both polarization directions E ⊥ c and E ‖ c. The parameters of 9 E modes and 4 A2 modes are determined by a dispersion analysis of the spectra. Three additional A2 modes are detected by infrared transmission measurements. The results obtained are compared with previous Raman scattering and two-phonon combination mode spectra.

Localized vibrational modes in proton and deuteron implanted GaP single crystals

Abstract Infrared absorption spectra of proton and deuteron implanted InP single crystals exhibit four localized vibrational modes with frequencies of 2197, 2212, 2308, 2335 cm -1 and 1600, 1619, 1659, 1678 cm -1 , respectively. From a comparison of these mode frequencies with those in other species containing In-H(D) and P-H(D) bonds it is concluded that all four modes observed are due to stretching vibrations of bonds formed between phosphorus and the implanted atoms. The number of vibrating bonds is found to be proportional to the damage density. Annealing experiments indicate a higher thermal stability of the defect configurations giving rise to the two high-energy localized modes.

Infrared reflectivity of Ag6Ge10P12

Abstract Infrared reflectivity spectra of p -type Ag 6 Ge 10 P 12 single crystals were measured at room temperature in the wavenumber range from 180 to 4000 cm -1 . Fits to a dielectric function including contributions from lattice oscillators and free carriers gave the parameters of five lattice vibrational modes and an effective hole mass of m p / m o = 2.3.

Infrared lattice vibrations and crystal structure of Cu2GeS3

The infrared reflectivity spectra were recorded at room temperature in the wavenumber range ν=180 to 4000 cm −1 using incident radiation polarized parallel to the respective crystal axes and perpendicular to the plane of incidence. The resulting spectra for the two polarization directions E∥a 0 and E∥b 0 are shown for the wavenumber range ν=180 to 500 cm −1 . No further structures were observed at ν>500 cm −1