Current-Induced Spin Photocurrent in GaAs at Room Temperature

Circularly polarized photocurrent, observed in p-doped bulk GaAs, varies nonlinearly with the applied bias voltage at room temperature. It has been explored that this phenomenon arises from the current-induced spin polarization in GaAs. In addition, we found that the current-induced spin polarization direction of p-doped bulk GaAs grown in the (001) direction lies in the sample plane and is perpendicular to the applied electric field, which is the same as that in GaAs quantum well. This research indicates that circularly polarized photocurrent is a new optical approach to investigate the current-induced spin polarization at room temperature.

Optical characteristics of type-II hexagonal-shaped GaSb quantum dots on GaAs synthesized using nanowire self-growth mechanism from Ga metal droplet

We report the growth mechanism and optical characteristics of type-II band-aligned GaSb quantum dots (QDs) grown on GaAs using a droplet epitaxy-driven nanowire formation mechanism with molecular beam epitaxy. Using transmission electron microscopy and scanning electron microscopy images, we confirmed that the QDs, which comprised zinc-blende crystal structures with hexagonal shapes, were successfully grown through the formation of a nanowire from a Ga droplet, with reduced strain between GaAs and GaSb. Photoluminescence (PL) peaks of GaSb capped by a GaAs layer were observed at 1.11 eV, 1.26 eV, and 1.47 eV, assigned to the QDs, a wetting-like layer (WLL), and bulk GaAs, respectively, at the measurement temperature of 14 K and excitation laser power of 30 mW. The integrated PL intensity of the QDs was significantly stronger than that of the WLL, which indicated well-grown GaSb QDs on GaAs and the generation of an interlayer exciton, as shown in the power- and temperature-dependent PL spectra, respectively. In addition, time-resolved PL data showed that the GaSb QD and GaAs layers formed a self-aligned type-II band alignment; the temperature-dependent PL data exhibited a high equivalent internal quantum efficiency of 15 ± 0.2%.

Optical characteristics of type-II hexagonal shaped GaSb Quantum dots on GaAs synthesized using nanowire self-growth mechanism from Ga metal droplet

We report the growth mechanism and optical characteristics of type-II band-aligned GaSb quantum dots (QDs) grown on GaAs using droplet epitaxy-driven nanowire formation mechanism in with molecular beam epitaxy (MBE). Using transmission electron microscope (TEM) and scanning electron microscope (SEM) images, we confirmed that the QDs, which comprise zinc-blende crystal structures with hexagonal shape, were successfully grown through the formation of a nanowire from a Ga droplet with less strain between GaAs and GaSb. Photoluminescence (PL) peaks of GaSb, which are capped by the GaAs layer, are observed at 1.11 eV, 1.26 eV, and 1.47 eV, assigned to the QDs, a wetting-like layer (WLL), and bulk GaAs, respectively, at the measurement temperature of 14 K and excitation laser power of 30 mW. The integrated PL intensity of the QDs is significantly stronger than the WLL, which indicates well-grown GaSb QDs on GaAs and the generation of an interlayer exciton, as shown in the power and temperature-dependent PL, respectively. In addition, Time-resolved PL (TRPL) data show that the GaSb QD and GaAs layer form a self-aligned type-II band alignment, and temperature-dependent PL data exhibit a high equivalent internal quantum efficiency of 15+/-0.2%.

Релаксация электронного спина и резонансное охлаждение ядерных спинов в структурах GaAs : Mn

The behavior of the electron spin relaxation time in bulk GaAs layers doped with Mn was studied experimentally. We investigated the dependence of the degree of circular polarization of photoluminescence in transverse and longitudinal magnetic fields. An increase in the relaxation time of the electron spin is found from 25 ns at low pumping power to 400 ns at the threshold pumping power. The effect of resonant cooling of the nuclear spin system by optically oriented electron spins is demonstrated.