N. V. Dikareva

Waveguide effect of GaAsSb quantum wells in a laser structure based on GaAs

The waveguide effect of GaAsSb quantum wells in a semiconductor-laser structure based on GaAs is studied theoretically and experimentally. It is shown that quantum wells themselves can be used as waveguide layers in the laser structure. As the excitation-power density attains a value of 2 kW/cm2 at liquid-nitrogen temperature, superluminescence at the wavelength corresponding to the optical transition in bulk GaAs (at 835 nm) is observed.

Stimulated emission from an InGaAs/GaAs/AlGaAs heterostructure grown on a Si substrate

High-perfection artificial Ge/Si substrates are created by hot-wire chemical-vapor deposition, and InGaAs/GaAs/AlGaAs quantum-well heterostructures are grown on these substrates by metalorganic chemical-vapor deposition. Photoluminescence spectra of these heterostructures are investigated. Stimulated emission in the near-infrared spectral range under optical pumping is observed. Threshold pump powers for the onset of stimulated emission are determined and the variation of the emission spectra with the optical-pump power is examined.

Emission properties of heterostructures with a (GaAsSb-InGaAs)/GaAs bilayer quantum well

The specific features of the emission characteristics of GaAs-based heterostructures with a GaAs1 − xSbx-InyGa1 − yAs bilayer quantum well are studied. The heterostructures are grown by metal-organic chemical vapor deposition (MOCVD). With an analysis of previously reported data on the MOCVD growth process taken into account, the temperature range (560–580°C), the relation between the fluxes emitted by the sources of Group-V and −III elements (≲1), and the order of layer growth for the production of the active region of a GaAs/InGaP laser heterostructure are determined experimentally. The active region is a GaAs0.75Sb0.25-In0.2Ga0.8As bilayer quantum well. For the structure, a 1075-nm electroluminescence signal attributed to indirect transitions between the valence band of the GaAs0.75Sb0.25 layer and the conduction band of the In0.2Ga0.8As layer is observed. An increase in the continuous-wave pump current yields a decrease in the 1075-nm emission intensity and initiates stable lasing at a wavelength of 1022 nm at a threshold current density of 1.4 kA cm−2 at room temperature. Lasing occurs at transitions direct in coordinate space.

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.

The waveguide effect of InGaAs quantum wells in a GaAs structure on Si substrate with Ge buffer layer

The waveguide effect of InGaAs quantum wells in a GaAs structure grown on a Si substrate with a relaxed Ge buffer layer has been studied. After an excitation power density of 35 kW/cm2 was reached at liquid-nitrogen temperature, several stimulated emission lines were observed in the energy range of 1350–1360 meV.

Optimization of InGaP/GaAs/InGaAs heterolasers with tunnel-coupled waveguides

The optimization of InGaP/GaAs/InGaAs laser structures with tunnel-coupled waveguides with the aim of reducing the directivity diagram is presented. The width of the directivity diagram in the plane normal to the p–n junction is reduced to 28° in the lasers produced.

Effect of thermal annealing on the emission properties of heterostructures containing a quantum-confined GaAsSb layer

Heterostructures containing single GaAsSb/GaAs quantum wells and bilayer GaAsSb/InGaAs quantum wells are produced by metal-organic vapor-phase epitaxy at atmospheric pressure. The growth temperature of the quantum-confined layers is 500–570°C. The structural quality of the samples and the quality of heterointerfaces of the quantum wells are studied by the high-resolution transmission electron microscopy of cross sections. The emission properties of the heterostructures are studied by photoluminescence measurements. The structures are subjected to thermal annealing under conditions chosen in accordance with the temperature and time of growth of the upper cladding p-InGaP layer during the formation of GaAs/InGaP laser structures with an active region containing quantum-confined GaAsSb layers. It is found that such heat treatment can have a profound effect on the emission properties of the active region, only if a bilayer GaAsSb/InGaAs quantum well is formed.

On a semiconductor laser with a p – n tunnel junction with radiation emission through the substrate

A multiwell interband cascade laser with a tunnel junction within a single waveguide and radiation emission through the substrate is implemented for the first time. It is shown that such a laser heterostructure design provides the more efficient population of quantum wells in comparison with a conventional multiwell laser with radiation emission through the substrate, due to which the lasing threshold is significantly lowered.

Dual-frequency GaAs/InGaP laser diode with a GaAsSb quantum well

The results of investigation of a metal-organic-vapor-phase-epitaxy-grown GaAsSb/GaAs/InGaP laser structure are presented. Steady two-band generation caused by spatially direct and indirect optical transitions is obtained. Observation of the sum frequency shows the effective intracavity mixing of modes in semiconductor lasers of such a type.

Effect of active-region “volume” on the radiative properties of laser heterostructures with radiation output through the substrate

The radiative properties of InGaAs/GaAs/InGaP laser structures with radiation output through the substrate depending on the number of quantum wells in the active region and laser diodes on their basis are investigated. It is established that the presence of six–eight quantum wells in the active region is optimum from the viewpoint of observable values of the threshold current and the output optical power of lasers.