Межзонный двухфотонный линейно-циркулярный дихроизм в полупроводниках в приближении Кейна

Interband two-photon optical transitions are classified and expressions are obtained for the matrix elements in a narrow-gap semiconductor depending on the band parameters, degree of polarization, and light frequency. It is shown that the main contribution to two-photon linear-circular dichroism in narrow-gap semiconductors is made by optical transitions proceeding from the subband of light holes to the conduction band. The dependences of the partial coefficients of interband two-photon absorption of light, which differ from each other by the types of optical transitions, are analyzed depending on the degree of polarization of the light, and a quantitative analysis of the coefficient of linear-circular dichroism of two-photon absorption of light is carried out. Expressions are obtained for the spectral dependence of the coefficient of interband two-photon absorption of light in narrow-gap semiconductors in the Kane model.

Диодные гетероструктуры с ферромагнитными узкозонными полупроводниками A-=SUP=-3-=/SUP=-FeB-=SUP=-5-=/SUP=- разного типа проводимости

Diode structures with ferromagnetic narrow-gap semiconductors A3FeB5 as only p-region (p-GaFeSb/n-InGaAs), only n-region (n-InFeSb/p-InGaAs), p- and n-regions (p-GaFeSb/n-InFeSb, p-GaFeSb/n-InFeAs) for p-n junction were fabricated by pulsed laser deposition in vacuum. The composition of ferromagnetic semiconductor layers and their thicknesses, determined by X-ray photoelectron spectroscopy, generally correspond to the technological data for diode structures. In particular, the thickness of the GaFeSb layer is 25–30 nm, and the thickness of the InFeAs and InFeSb layers is 35–40 nm. The iron content in InFeSb ranges from 25 to 35 at.%. The GaFeSb layer contains from 15 to 41 iron at. %, and the InFeAs layer - 35 iron at. %. The chemical analysis of the structures revealed the presence of chemical bonds Fe-As (Sb), In-Fe and Fe-Ga. Therefore, it can be assumed that Fe atoms in the fabricated structures can substitute for elements of groups III and V simultaneously. All structures exhibit the effect of negative magnetoresistance at sufficiently low observation voltages of the effect (up to 50 mV), in low magnetic fields (up to 3600 Oe), and at high measurement temperatures. For GaFeSb/InFeSb, GaFeSb/InFeAs diodes, negative magnetoresistance was first observed at room temperature. The hysteresis form of the dependences of the resistance on the magnetic field suggests the effect of the ferromagnetic properties of the layers of narrow-gap semiconductors on the transport of carriers in the structures.

Modeling on the temperature dependence of the magnetic susceptibility and electrical conductivity oscillations in narrow-gap semiconductors

Electrical conductivity oscillations, magnetic susceptibility oscillations and electronic heat capacity oscillations for narrow-gap electronic semiconductors are considered at different temperatures. A theory is constructed of the temperature dependence of quantum oscillation phenomena in narrow-gap electronic semiconductors, taking into account the thermal smearing of Landau levels. Oscillations of longitudinal electrical conductivity in narrow-gap electronic semiconductors at various temperatures are studied. An integral expression is obtained for the longitudinal conductivity in narrow-gap electronic semiconductors, taking into account the diffuse broadening of the Landau levels. A formula is obtained for the dependence of the oscillations of longitudinal electrical conductivity on the bandgap of narrow-gap semiconductors. The theory is compared with the experimental results of [Formula: see text]. A theory is constructed of the temperature dependence of the magnetic susceptibility oscillations for narrow-gap electronic semiconductors. Using these oscillations of magnetic susceptibility, the cyclotron effective masses of electrons are determined. The calculation results are compared with experimental data. The proposed model explains the experimental results in [Formula: see text] at different temperatures.