Far-infrared reflectivity study of lattice dynamics of narrow-gap HgCdMnTe semiconductors

Abstract

We report the results of a comprehensive study of lattice dynamics by means of far-infrared phonon spectroscopy in quaternary semimagnetic narrow-gap Hg 1−x−y Cd x Mn y Te single crystals. A new version of the isodisplacement model is developed which takes into account the peculiarities of the dielectric function of narrow-gap semiconductors. This new approach is used to describe the phonon spectra transformation with composition for quaternary materials and is found to be in excellent agreement with the experimental data. The evidence for better quality and more stabilized crystalline structure of Hg 1−x−y Cd x Mn y Te in comparison with ternary Hg 1−x Cd x Te is presented and ascribed to the effect of magnetic doping.

Magnetophonon resonance in Mn Cd Hg1−−Te and Zn Cd Hg1−−Te

“…Detailed investigation of phonon spectra in ZMCT [3,5], shows that the frequency of the HgTe-like mode is very weakly dependent on composition and the investigation of the phonon spectra of MMCT [6] confirms this weak dependence. This basic phonon mode corresponds to the HgTe-like one.…”

“…The phonon spectra of MMCT solid solutions were studied by Tarasov et al [6]. Phonon frequencies and energies of LO-phonons are presented in Table 2 for the two compositions of MMCT available in [6].…”

Manganese concentration effect on the lattice dynamics in multinary spin doped semiconductors

“…The microscopic approach [10,23], that takes into account the electronic correlations allows an explanation for the appearance of a local double-well potential for one type of crystal constituent ions as a consequence of the specific electronic excitations generation. Namely, the electron-hole pairs originating from the p and d states that are dressed with the transverse optical phonon cloud.…”

“…When the Cd and Mn contents were changed simultaneously, the energy gap was maintained at approximately the same value. In order to get the information about the phonon modes the reflection spectra have been treated by subsequently applying the Kramers-Kronig and dispersion analyses [10] with the dielectric function (ω) taken in the form typical for the narrow-gap semiconductors [11]. The results of such treatment are presented in Figs.…”

“…Each spectrum presents four conventional regions: the region below 110 cm −1 is defined in the main by defect and clustering modes; the region close to 130 cm −1 reflects the LO-TO splitting of the Hg-Te-like mode; the region near 150 cm −1 contains the LO-TO splitting of Cd-Te-like mode; and that in the vicinity of 190 cm −1 includes the Mn-Te-like vibrations[10]. The spectrum transformation due to the cadmium concentration change with the Mn concentration approximately invariable can be seen fromFig.…”