<title>Determining of the material parameters of Zn<formula><inf><roman>x</roman></inf></formula>Cd<formula><inf><roman>y</roman></inf></formula>Hg<formula><inf><roman>1-x</roman></inf></formula>-<formula><inf><roman>y</roman></inf></formula>Te by magnetophonon spectroscopy</title>

Abstract

The phonon and electron subsystems were studied in quaternary solid solutions of ZnxCdyHgl. -yTe (ZMCT) by means of Raman scattering and Magnetophonon Resonance. The Raman spectra of several compositions confirm the three-mode behaviour of phonon spectra. The cluster mode has also been observed. Four kinds of LO-phonons (of HgTe-like, CdTe-like and ZnTe-like sublatticies and ZnTe-clusters) participate in the electron-phonon interaction. Four types of one-phonon Magnetophonon Resonances and two types of Magnetophonon Resonances on the difference of phonon frequencies have been observed. Keywords: magnetophonon resonance, semiconductors 1. INTRODUCTION Random homogenous substitutions of matrix cations by another metal atoms in the solid solution lattices with common anion (as is the case in GaAs-AlAs or HgTe-CdTe) is known to cause a continuous reconstruction of the electronic structure and the phonon spectra with composition variation. It may be assumed that the introduction of a third cation will enable us to obtain a supplementary degree of freedom in the control of material parameters. It has an additional advantage in the case of HgTe-CdTe (MCT), because the introduction of Zn-atoms stabilises the weak Hg-Te bonds in crystal lattice of this solid solution, whereas he presence of Cd-atoms destabilises them 1-3. The introduction of the fourth component Zn causes not only a simple extension of the physical properties of MCT, but also new phenomena, connected with multimodeness of the crystal lattice. 'Multimodeness' is an issue of primary significance in the study of four-component solid solutions. ZMCT has three sublattices (ZnTe-like, CdTe-like and HgTe-like). Therefore, a three-mode behaviour of the phonon spectrum in this solid solution may be predicted. Other possibilities also exist 4. The present article discusses of ZMCT structures investigated of ZMCT by means of Magnetophonon Resonance (MPR) experiments, a powerful tool for the investigation of electron and hole spectra '. A series of films of ZMCT obtained by liquid-phase epitaxy on CdTe substrates have been studied. The thickness of homogeneous layers is d = 41tm. The temperature dependencies of electroconductivity and Hall coefficient measured in those structures have shown an activated behaviour. The quality of epitaxial layers investigated by MPR is comparable with the corresponding high quality MCT alloys with the same energy gap (near 180 -300 meV). The mobility of electrons in those layers is sufficiently high to observe the MPR. It is important to note that the parameters of these samples have not changed over the period of three years, whereas MCT samples are characterised by the temporal degradation of parameters.