Magnetooptical Study of Zeeman Effect in Mn modulation-doped InAs/InGaAs/InAlAs Quantum Well Structures

We report on a magneto-photoluminescence (PL) study of Mn modulation-doped InAs/InGaAs/InAlAs quantum wells. Two PL lines corresponding to the radiative recombination of photoelectrons with free and bound-on-Mn holes have been observed. In the presence of a magnetic field applied in the Faraday geometry both lines split into two circularly polarized components. While temperature and magnetic field dependences of the splitting are well described by the Brillouin function, providing an evidence for exchange interaction with spin polarized manganese ions, the value of the splitting exceeds the expected value of the giant Zeeman splitting by two orders of magnitude for a given Mn density. Possible reasons of this striking observation are discussed

Spin-polarized electric currents in diluted magnetic semiconductor heterostructures induced by terahertz and microwave radiation

We report on the study of spin-polarized electric currents in diluted magnetic semiconductor (DMS) quantum wells subjected to an in-plane external magnetic field and illuminated by microwave or terahertz radiation. The effect is studied in (Cd,Mn)Te/(Cd,Mg)Te quantum wells (QWs) and (In,Ga)As/InAlAs:Mn QWs belonging to the well known II-VI and III-V DMS material systems, as well as, in heterovalent AlSb/InAs/(Zn,Mn)Te QWs which represent a promising combination of II-VI and III-V semiconductors. Experimental data and developed theory demonstrate that the photocurrent originates from a spin-dependent scattering of free carriers by static defects or phonons in the Drude absorption of radiation and subsequent relaxation of carriers. We show that in DMS structures the efficiency of the current generation is drastically enhanced compared to non-magnetic semiconductors. The enhancement is caused by the exchange interaction of carrier spins with localized spins of magnetic ions resulting, on the one hand, in the giant Zeeman spin-splitting, and, on the other hand, in the spin-dependent carrier scattering by localized Mn2+ ions polarized by an external magnetic field.Comment: 14 pages, 13 figure

Exchange interaction of electrons with Mn in hybrid AlSb/InAs/ZnMnTe structures

Diluted magnetic semiconductor heterovalent AlSb/InAs/ZnMnTe quantum well (QW) structures with an electron channel have been designed and grown applying molecular-beam epitaxy. The enhanced magnetic properties of QWs as a result of the exchange interaction with Mn2+ ions, are proved by measuring the microwave radiation induced spin polarized electric currents

InSb Quantum Dots in an InAsSb Matrix Grown by Molecular Beam Epitaxy

We report on molecular beam epitaxy of InSb insertions in InAs and InAsSb matrices, emitting at wavelengths beyond 4μm. Different growth techniques for deposition of InSb quantum dots in the 1-2 monolayer range of the InSb nominal thickness, namely conventional molecular beam epitaxy and migration enhanced epitaxy, as well as different matrices (InAs and InAsSb) have been employed for increasing the emission wavelength of the InSb/InAs nanostructures. The formation of InSb quantum dots has been studied in situ using reflection high energy electron diffraction and ex situ by using transmission electron microscopy. The peculiarities of In(Ga)AsSb alloys growth and compositional control are also discussed. Bright photoluminescence up to 4.5μm has been observed at 80 K

Magneto-Optical Studies of Narrow Band-Gap Heterostructures with Type II Quantum Dots InSb in an InAs Matrix

Magneto-optical properties of type II heterostructures with InSb/InAs quantum dots has been studied at external magnetic field applied in the Faraday geometry. The emission polarization degree can be changed in the range from 100% σ-minus to 10% σ-plus due to excitation intensity and temperature variation. The detailed calculation of the band structure within a tight-binding approximation is presented. The simulation of the experimental data reveals that the oscillator strength of the optical transitions involving electrons with the spin oriented along and opposite to the magnetic field vector differs by approximately 1.8 times in the heterostructures under study

GaAs in GaSb : strained nanostructures for mid-infared optoelectronics

Molecular beam epitaxy was used for the first time to grow novel GaAs/GaSb heterostructures with ultrathin (0.8–3 monolayers) GaAs layers embedded in GaSb. These structures were studied by X-ray diffraction, transmission electron microscopy, and photoluminescence. By contrast to known structures with self-assembled quantum dots, GaAs layers in GaAs/GaSb structures are subject to elastic tensile stresses due to 7% lattice mismatch. The structures exhibit intense photoluminescence in the 2 µm region at low temperatures. Quantum-dimensional islands are formed in the structure at a nominal GaAs layer thickness exceeding 1.5 monolayers. The band alignment of the structures is of type II.5 page(s