g factor of electrons in an InAs quantum well

Theory of g-factor enhancement in narrow-gap quantum well heterostructures

We report on the study of the exchange enhancement of the g-factor in the two-dimensional (2D) electron gas in n-type narrow-gap semiconductor heterostructures. Our approach is based on the eight-band k⋅p Hamiltonian and takes into account the band nonparabolicity, the lattice deformation, the spin-orbit coupling and the Landau level broadening in the δ-correlated random potential model. Using the 'screened' Hartree-Fock approximation we demonstrate that the exchange g-factor enhancement not only shows maxima at odd values of Landau level filling factors but, due to the conduction band nonparabolicity, persists at even filling factor values as well. The magnitude of the exchange enhancement, the amplitude and the shape of the g-factor oscillations are determined by both the screening of the electron-electron interaction and the Landau level width. The 'enhanced' g-factor values calculated for the 2D electron gas in InAs/AlSb quantum well heterostructures are compared with our earlier experimental data and with those obtained by Mendez et al (1993 Phys. Rev. B 47 13937) in magnetic fields up to 30 T.

Magnetoelectric photocurrent generated by direct interband transitions in InGaAs/InAlAs two-dimensional electron gas

We report the observation of magnetoelectric photocurrent generated via direct interband transitions in an InGaAs/InAlAs two-dimensional electron gas by a linearly polarized incident light. The electric current is proportional to the in-plane magnetic field, which unbalances the velocities of the photoexcited carriers with opposite spins and consequently generates the electric current from a hidden spin photocurrent. The spin photocurrent can be evaluated from the measured electric current, and the conversion coefficient of spin photocurrent to electric current is self-consistently estimated to be 10(-3)-10(-2) per Tesla. The observed light-polarization dependence of the electric current is well explained by a theoretical model which reveals the wave vector angle dependence of the photoexcited carrier density.

OPTICALLY-DETECTED MICROWAVE RESONANCE IN InGaAsN/GaAs QUANTUM WELLS AND InAs/GaAs QUANTUM DOTS EMITTING AROUND 1.3 μm

Optically-detected magnetic resonance (ODMR) and optically-detected cyclotron resonance (ODCR) were applied to study two types of nanostructures emitting around 1.3 μm: quantum wells with low nitrogen content and InAs / GaAs quantum dots (both isolated and vertically-coupled). ODMR with the axial symmetry (effective g factor |g‖|=3.61 and |g⊥|=0.7) was found in unannealed InGaAsN / GaAs multiple-quantum well structures and ascribed to electrons in the quantum wells; the sign of g factor is suggested to be negative. There is evidence that before annealing the InGaAsN / GaAs structure has properties, which are typical for quantum wells, but after annealing the structure is completely-changed and resembles a quantum-dot-like structure. The effect of cyclotron resonance on the luminescence of InAs quantum dots was found. The observed ODCR seems to belong to a two-dimensional system, such as a heterointerface InAs / GaAs .