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Optical and transport properties of diamondlike and multinary compounds
Phone (+994 12) 5395163
Chief  Abdullayev Nadir Allahverdi oglu

Doctor in Physics

Total number of employees 15
Basic activity directions   The main scientific direction of laboratory is the establishment of features of a  energy spectrum formation, influence of external factors (temperature, pressure, scale and x-ray irradiations, various impurities) on electronic, phonon spectra and the phenomena of charge transfer in semiconducting compounds.

The field of investigated compounds is wide - layered compounds АIIIВVI (А-Ga,In, C-S,Sе,Te), АV2ВVI3 (А-Bi,Sb, C- Sе,Te), АIIIВIIIСVI2 (А-Tl, B-Ga,In, C-S,Se,Te) and complex diamondlike compounds, crystallizing in a tetragonal structure АIIВIII2СVI4 (А-Сd,Zn, B-Ga,In, C-S,Se,Te), AIBIIIC2VI (А-Сu,Ag, B-Ga,In, C-S,Se,Te) type.

Main scientific achievements  1. The following main results are obtained:

a) CdGa2S4, CdGa2Se4, ZnGa2Se4 and solid solutions on their base were synthesized and growth. X-ray analysis have been investigated, theory-group analysis of electronic states at high simmetrical points of Brillouin zone;

b) As a result of joint analysis of experimental results and theory-group researches the character of optical transitions in highsymmetrical points of Brilliounzone Г (000); structure of valence band top was established and valence band top parametres-crystal and spin-orbital splitting were calculated, it also was established that the p-states of trivalent atoms bring basic contribution to the formation of valence band top.

c) From the temperature dependence of optical absorption edge the deformation potentials of valence band top and conduction band bottom have been calculated.

2. The following part of the reseaches is connected with the investigation of lattice dinamics of the tetraqonal compounds:

a) Infrared reflectivity and Raman scattering spectra have been investigated. The observed phonon frequences were identified by the symmetry types. b) By theory-group method symmetrical motions of atoms of the unit cell were constructed. c) In the result of joint analysis of optical phonons and symmetrical motions of atoms of the unit cell conformity between phonon frequencies and motion of atoms of unit cell have been established. d) Within the force constants model the force constants of interatoms bond were calculated. Nature of chemical bonds was established. e) As the result of analysis of temperature dependence of optical phonons of CdGa2 Se4 there have been established that the phonon-phonon interaction on a-b plane takes place. f) Dependence of optical phonons on pressure in range 0-20GPa have been investigated. Pressure coefficient, Grunaizen parameter, volume bulk modulus has been calculated. g) The following cycle of researches is connected with investigation of nonequlibrium processes (photoconductivity, photoluminescence) and effect of external factors (temperature, impurities, intensity of incident radiation and etc.) in tetragonal compounds. As the result of investigations spectra of local states, their parameters, mechanism of generation-recombination processes has been established.

3. The electric and galvanomagnetic phenomena in the wide temperature interval (1,2-300K) and magnetic fields (0-8T) in strongly anisotropic layered crystals of АIIIВVI and АV2BVI3 type and solid solutions on their base was investigated. Features of charge transfer in various crystallographic directions and temperature ranges, influence of various impurities on the type of conductivity, mobility and concentration of charge carriers was established, characteristic parametres of the local centres (density of the local centres, concentration and radius of the localized centres) was calculated.

Above listed results are valuable contribution to solid state physics. These results are useful in explanation of physical processes taken place in semiconductors, calculations of energy spectra, explanation thermal processes, calculations of thermodynamical parameters and etc.

The results were published in deferent journals. The published works have been quoted in 291 scientific journals, 126 of them quoted since 2010.