Ferromagnetic HfO2/Si/GaAs interface for spin-polarimetry applications

In this letter, we present electrical and magnetic characteristics of HfO2-based metal-oxide-semiconductor capacitors (MOSCAPs), along with the effect of pseudomorphic Si as a passivating interlayer on GaAs(001) grown by molecular beam epitaxy. Ultrathin HfO2 high-k gate dielectric films (3–15 nm) have been grown on Si/GaAs(001) structures through evaporation of a Hf/HfO2 target in NO2 gas. The lowest interface states density Dit at Au/HfO2/Si/GaAs(001) MOS-structures were obtained in the range of (6−13)×101

Semiconductor A3B5 nanostructures for infrared femtosecond lasers

Two techniques were suggested and tested for the recovery time shortening of saturable absorbers on a base of A3B5 compounds including quantum wells. The first one, proposed by authors, is the sample post-growth treatment by UV laser radiation; it implied generation of point defects, which, in its turn, led to electron-hole recombination acceleration and to recovery time shortening by an order of magnitude and more. Another technique based on special design of barriers gave promising results for the fast saturable absorbers. Semiconductor mirrors designed for Yb3+:KY(WO4)2 infrared laser mode locking led to 115 fs stable modelocking regime with average power close to CW operation. Results on fast saturable absorbers for spectral region of 1500 nm are also presented

Raman and infrared spectroscopical investigation of the optical vibrational modes in GaSb/AlSb superlattices

The vibrational spectrum of ultra-thin layer GaSb/AlSb superlattices was investigated in detail by infrared (IR) and Raman spectroscopies. The effect of confinement of the transverse and longitudinal optical phonons in both types of the layers was studied. The dispersions of optical phonons of the GaSb and the AlSb obtained from the analysis of the Raman and IR spectra are in a good accordance with the theoretical data and results of neutron scattering experiments. First- and second-order Raman spectroscopy indicates the presence of intermixture of atoms at the interfaces in the GaSb/AlSb superlattices

Capacitance study of electron traps in low-temperature-grown GaAs

International audienceElectron traps in GaAs grown by MBE at temperatures of 200–300°C (LT-GaAs) were studied. Capacitance deep level transient spectroscopy (DLTS) was used to study the Schottky barrier on n-GaAs, whose space-charge region contained a built-in LT-GaAs layer ∼0.1 µm thick. The size of arsenic clusters formed in LT-GaAs on annealing at 580°C depended on the growth temperature. Two new types of electron traps were found in LT-GaAs layers grown at 200°C and containing As clusters 6–8 nm in diameter. The activation energy of thermal electron emission from these traps was 0.47 and 0.59 eV, and their concentration was ∼1017 cm−3, which is comparable with the concentration of As clusters determined by transmission electron microscopy. In LT-GaAs samples that were grown at 300°C and contained no arsenic clusters, the activation energy of traps was 0.61 eV. The interrelation between these electron levels and the system of As clusters and point defects in LT-GaAs is discussed