Experimental determination of the optimum number of quantum wells in multiwell heterolasers with radiation leakage into a substrate

The dependence of the mode structure and threshold characteristics of laser diodes with significant (～94%) radiation leakage into a substrate on the number of quantum wells (QWs) in a laser-diode heterostructure has been studied. It is established that laser diodes with a small number of QWs generate on the fundamental waveguide mode. As the number of QWs increases, the first waveguide mode begins to dominate and the threshold current increases, which is probably related to a weak filling of central QWs with nonequilibrium carriers and increased losses of the fundamental mode.     

GaAs-Based Laser Diode with InGaAs Waveguide Quantum Wells

Semiconductors - The results of studying a GaAs-based laser with InGaAs waveguide quantum wells, which operates at room temperature in the electric-pumping mode, are presented. The minimal...     

Effect of periodic interruption of the atmospheric-pressure MOVPE growth of InAs/GaAs quantum dots on their morphology and optoelectronic spectra

A modified regime of growing InAs/GaAs quantum dots (QDs) by metalorganic vapor phase epitaxy (MOVPE) at atmospheric pressure is described. In contrast to the standard growth regime, the time of periodic interruption of the supply of trimethylindium and arsin to the reactor was increased and varied from 4 to 18 s. It is shown that optimization of the interruption time leads to the formation of dense, homogeneous (with respect to dimensions) QD arrays and to a decrease in the concentration of coarse relaxed clusters without using additional treatments (e.g., doping with surfactants, chemical etching). In particular, the surface concentration of QDs increases up to 6 × 10¹⁰ cm⁻², that is, by almost an order of magnitude as compared to the standard growth regime. QD structures grown using the modified MOVPE method are characterized by high thermal stability and ensure high intensity of room-temperature electroluminescence of the related edge-emitting Schottky diodes.     

Efficient generation of the first waveguide mode in the InGaAs/GaAs/InGaP heterolaser

Generation of the first excited transverse mode (TE₁) in a new InGaAs/GaAs/InGaP diode heterolaser with a thin InGaP layer at the waveguide center was studied. This laser design decreases the competition of the first and fundamental modes and provides TE₁ mode lasing at a threshold current comparable to that of an ordinary laser oscillating at the fundamental TE₀ mode.     

A hydrogen-sensitive structure based on semi-insulating gallium arsenide

The response characteristics of a simple hydrogen-sensitive structure based on semi-insulating single crystal gallium arsenide with planar palladium electrodes deposited onto the oxidized substrate surface are studied. It is demonstrated that such structures exhibit a fast response to hydrogen present in the gas phase. The sensitivity can be increased by growing, prior to the electrode formation, an intermediate epitaxial GaAs film with built-in strained quantum-confined layers of InGaAs and InAs onto the semi-insulating GaAs substrate.     

Circularly polarized electroluminescence of quantum-size InGaAs/GaAs heterostructures with ferromagnetic metal-GaAs Schottky contacts

Electroluminescence (EL) of InGaAs/GaAs heterostructures with quantum wells and ferromagnetic metal (Co, Ni)/GaAs Schottky contacts has been studied in magnetic fields up to 10 T at a temperature of 1.5 K. The EL line corresponding to the recombination of electrons with injected holes exhibits splitting into components corresponding to the Landau levels in the applied magnetic field and shows circular polarization that significantly exceeds the level typical of such structures with nonmagnetic (Au/GaAs) contacts. The degree of circular polarization (P _EL) exhibits a nonmonotonic dependence on the applied magnetic field and is correlated with the filling of Landau levels. The maximum degree of circular polarization reached in the heterostructures studied is P _EL = 40%.     

Spin effects in magnetoresistance induced in an <Emphasis Type="Italic">n</Emphasis>-In<Subscript>x</Subscript>Ga<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>As/GaAs double quantum well by a parallel magnetic field

Magnetoresistance in n-In_xGa_1?xAs/GaAs (x ≈ 0.18) heterostructures with double quantum wells (DQWs) was studied in the magnetic field parallel to the DQW layer. Specific features of the magnetoresistance, related to the passing of the tunnel gap edges across the Fermi level, are revealed and studied. Agreement between the calculated and experimental positions of the observed features is obtained when the spin splitting of the energy spectrum is taken into account. Earlier, similar features were observed in the magnetoresistance of n-GaAs/Al_xGa_1?xAs DQW heterostructures, but the spin effects did not manifest themselves.     

On the Combined Application of Raman Spectroscopy and Photoluminescence Spectroscopy for the Diagnostics of Multilayer Heterostructures

Semiconductors - The results of studying GaInAs/GaInP/GaAs photodiode structures grown by metal–organic vapor-phase epitaxy are reported. A procedure for the diagnostics of such multilayer...     

Features of the selective manganese doping of GaAs structures

The effect of technological parameters on the selective manganese doping of arsenide–gallium heterostructures fabricated by a combination of methods of MOS-hydride epitaxy and pulsed-laser deposition is investigated. As these parameters, the impurity content in the manganese δ layer and the structureformation temperature are used. It is established that the prepared structures demonstrate the highest electrical activity and have ferromagnetic properties at a growth temperature of ~400°C and an impurity content of no higher than 0.2–0.3 monolayers. Studying the grown structures by the methods of reflection spectroscopy, high-resolution transmission electron microscopy, and secondary-ion mass spectrometry shows that use of the above conditions in the case of pulsed laser deposition makes it possible to obtain arsenide–gallium structures, which have good crystalline quality, and manganese is concentrated in them within a thin (7–8 nm) layer without substantial diffusion-induced spreading and segregation.