Optical and photoelectric properties of anisotropic semiconductors

Members of the group

• O.G. Koshelev

Results

Spectra of optical absorption, photoconductivity and short-circuit photocurrent are known to be very informative for investigations of the peculiarities of the band structure. However the studies on these spectra for CdAs₂ and ZnAs₂ anisotropic crystals are very limited.
Using the mentioned methods CdAs₂ crystals were studied in a polarized light over the temperature range of 77-300 K, and two indirect and one direct interband optical transitions were observed. The energies of effective phonons, bonding energies of indirect excitons, and the temperature dependence of energy gap were determined.
The investigations of ZnAs₂ crystals with very low residual impurity concentration have unambiguously shown that the first absorption edge in ZnAs₂ is determined by indirect optical transitions. The excitonic absorption peak associated with direct interband transitions was observed in the 77-300 K temperature range. This observation was possible due to high structural perfection and purity of the studied crystals.

Selected publications:

• V.A. Morozova, D.I. Pishchikov, S.M. Loseva, O.G. Koshelev and S.F. Marenkin. Optical and photoelectric properties of ZnAs₂ single crystals. Fiz. i Techn. Poluprovodn. 25, 1664 (1991) (in Russian).

• V.A. Morozova, S.F. Marenkin, T.V. Semenenya, A.M. Raukhman, S.M. Loseva and O.G. Koshelev. Optical and photoelectric properties of CdAs₂ single crystals. Neorg. Mater. 30, 33 (1994) (in Russian).

• V.A. Morozova, T.V. Semenenya, S.M. Loseva, O.G. Koshelev, S.F. Marenkin, A.M. Raukhman. Determination of CdAs₂ band structure parameters from optical transmission and photoconductivity. Semiconductors 29, 199 (1995).

• V.A. Morozova, T.V. Semenenya, S.F. Marenkin, O.G. Koshelev, A.M. Raukhman, S.M. Loseva. Optical transitions in perfect undoped CdAs₂ single crystals at the edge of fundamental absorption and in the range of impurity absorption. Inorganic Materials 32, 10 (1996).