This study uses a numerical model to analyze the dynamics of high-power semiconductor lasers pumped by a high-repetition rate pulse sequence. It explores the distribution of photons and gain along the laser cavity and proposes an approach to optimize laser parameters for maximum efficiency and stability. The repetition rate range of interest spans from sub-MHz to several GHz.

Ridge-waveguide semiconductor lasers operating in CW up to 500 mW with one TE00 mode and up to 2 W with few TE modes at RT are demonstrated. Highly dense arrays with stable Gaussian lateral far field (10 emitters, $200\ \mu\mathrm{m}$ total aperture) are shown to demonstrate 5 W in CW and 25 W in pulsed mode at RT.

Thin aluminum nitride (AlN) films have been synthesized by reactive ion–plasma sputtering (RIPS) and their properties have been studied in view of using this method for obtaining protective coatings on output facets of high-power semiconductor laser cavities based on Al x Ga 1 − x As/GaAs heterostructures. Investigations by energy-dispersive X-ray spectroscopy and ellipsometry techniques showed that, at a residual pressure of ~10 –5 Torr, a layer of aluminum oxynitride is formed and the film–substrate heteroboundary may experience to oxidation. However, AlN films with thicknesses on the order of 100 nm grown in pure nitrogen at a residual pressure of ~10 –7 Torr were evidently free of oxygen and could reliably prevent its penetration to the region of heteroboundary.

Design of a structure with QWs distributed in a broadened waveguide layer is presented, which ensures mode selection, preserves the fundamental mode, provides minimum difference of optical confinement factors between QWs for matching the threshold conditions. A peak optical power of 15 W is demonstrated with a pulse width of 80 ps.

High-power lasers and mini diode laser bars based on AlGaAs/InGaAs/GaAs heterostructures (1060 nm) demonstrate high-efficient generation of pulses with durations in the range of 1-100 ns. It is shown that the use of heterothyristor arrays increases the pump current and output optical power.

The paper presents the results of the synthesis of thin aluminum nitride films by reactive ion-plasma sputtering and the study of their properties with the aim of using as the protective coatings for the high-power AlxGa1-xAs/GaAs semiconductor laser heterostructures. EDS studies and ellipsometry showed that at a residual pressure in the chamber of the order of ~10-5 Torr, a layer of aluminum oxynitride is formed in the films. In this case, the film-substrate heterointerface can undergo oxidation. However, AlN films with a thickness of the order of 100 nm grown in a pure nitrogen medium with a residual pressure of ~10-7 Torr apparently do not contain oxygen, and can reliably prevent its penetration into the heterointerface region. Potentially, they can serve as effective protection for oxidation sensitive heterostructures.

The concentration profiles of defects produced in structures upon the implantation of nitrogen ions into GaAs epitaxial layers with an uncovered surface and that covered with an AlN film and subsequent annealing are studied. The ion energies and the implantation doses are chosen so that the nitrogen-atom concentration profiles coincided in structures of both types. Rutherford proton backscattering spectra are measured in the random and channeling modes, and the concentration profiles of point defects formed are calculated for the samples under study. It is found that the implantation of nitrogen ions introduces nearly the same number of point defects into structures of both types, and the formation of an AlN film by ion-plasma sputtering is accompanied by the formation of an additional number of defects. However, the annealing of structures of both types leads to nearly the same concentrations of residual defects.

Thin nano-sized aluminum nitride films on GaAs (100) substrates with varying degrees of misorientation with respect to the <100> direction can be obtained by reactive ion-plasma deposition. It is shown that growth on substrates with different degrees of mismatch from the <100> direction leads to the growth of an AlN film with different phase composition and crystalline state. An increase in the degree of misorientation in the GaAs substrate used for growth is reflected both in the structural quality of nanoscale AlN films and in their electron structure, surface morphology, and optical properties. Thus, the management of the morphology, surface composition and optical functional characteristics of AlN/GaAs heterophase systems can be achieved by using the degree of misorientation of the GaAs substrates.

AbstractThe concentration profiles of defects produced in structures upon the implantation of nitrogen ions into GaAs epitaxial layers with an uncovered surface and that covered with an AlN film and subsequent annealing are studied. The ion energies and the implantation doses are chosen so that the nitrogen-atom concentration profiles coincided in structures of both types. Rutherford proton backscattering spectra are measured in the random and channeling modes, and the concentration profiles of point defects formed are calculated for the samples under study. It is found that the implantation of nitrogen ions introduces nearly the same number of point defects into structures of both types, and the formation of an AlN film by ion-plasma sputtering is accompanied by the formation of an additional number of defects. However, the annealing of structures of both types leads to nearly the same concentrations of residual defects.

A study of the surface topography and optical characteristics of thin AlN films used as passivating and antireflection coatings deposited on n-GaAs (100) substrates by reactive ion-plasma sputtering is reported. It was found that the process conditions affect the structure and the optical characteristics of the films, which makes it possible to obtain coatings with prescribed parameters. An analysis of the results furnished by ellipsometry and atomic-force microscopy of the surface shows that the refractive index of the films is correlated with the surface structure.

Thin AlN nanofilms are produced by reactive ion-plasma deposition onto GaAs(100) substrates misoriented with respect to the 〈100〉 direction to different degrees. It is shown that growth on substrates misoriented with respect to the 〈100〉 direction to different degrees results in the formation of AlN films with different phase compositions and crystal states. An increase in the degree of misorientation of the GaAs(100) substrate used for growth influences both the structural quality of AlN nanofilms and their electronic structure, surface morphology, and optical properties. Thus, the morphology, surface composition, and optical functional characteristics of AlN/GaAs(100) heterophase systems can be controlled using differently misoriented GaAs(100) substrates.

With the use of reactive plasma-ion deposition, thin nano-sized films of AlN were obtained on the substrates of GaAs(100) with a different degree of misorientation relative to the <100> direction.It was shown that the growth of the AlN films on GaAs substrates with a small degree of misorientation resulted in the formation of the AlN films in the nano-crystalline state. Hence, the film with a cubic crystal system was formed on a precisely oriented GaAs substrate, while on the substrate with 2° misorientation, the film consisted of a mixture of the AlN phases with cubic and hexagonal crystal symmetry. At the same time, the growth of the films on the substrates with a high degree of misorientation resulted in the disappearance of the long-range order in the crystalline structure of the AlN films; this implied the formation of the AlN phase in the amorphous state. The misorientation of the GaAs(100) substrate affected the sizes of the nano-islands formed on the surface of the AlN film. The lower the misorientation of the GaAs(100) substrate, the smaller were the lateral sizes of the nano-islands.Comparing our data for the optical band gap and the dispersion of the refractive index obtained by reactive ion-plasma deposition and the results for the AlN films grown by reactive sputtering, which is the closest method to the technology used in our work, we found that depending on the conditions of the reactive sputtering, nano-sized films of AlN with refractive index values within the range of 2.26–2.38 for the energy range of ∼4.7–4.9 eV and optical band gaps within 5.34–5.71 eV, were obtained. It was possible to obtain thin films with refractive index values within the range of 1.65–3.35 for energy values of ∼4.7–4.9 eV and optical band gaps of ∼5–6.2 eV by the application of the AlN deposition on the surface of semiconductor materials proposed in this study.An increase in the misorientation degree for the GaAs substrate was observed along with an improvement in the structural quality of nano-sized AlN films as well as in their electron structure, surface morphology, and optical properties. Thus, the morphology, surface composition, and optical functional characteristics of hetero-phase AlN/GaAs systems can be controlled by using GaAs substrates with a specified degree of misorientation relative to the <100> direction.

AbstractA study of the surface topography and optical characteristics of thin AlN films used as passivating and antireflection coatings deposited on n -GaAs (100) substrates by reactive ion-plasma sputtering is reported. It was found that the process conditions affect the structure and the optical characteristics of the films, which makes it possible to obtain coatings with prescribed parameters. An analysis of the results furnished by ellipsometry and atomic-force microscopy of the surface shows that the refractive index of the films is correlated with the surface structure.

In the work we investigate synthesis of aluminum nitride films using reactive ion plasma deposition in oxygen/nitrogen gas mixture for application as optical elements for power semiconductor lasers. The experimental refractive index of synthesized AlNO films is dependent on oxygen composition and is decreasing in diapason from 1.76 to 2.035 at elevation of the oxygen fraction.It is shown that the AlN films synthesized by pure nitrogen plasma are polycrystalline and textured. The oxygen presence in discharging gas results to growth of amorphous phase of the AlNO film.

AbstractIn the work we investigate synthesis of aluminum nitride films using reactive ion plasma deposition in oxygen/nitrogen gas mixture for application as optical elements for power semiconductor lasers. The experimental refractive index of synthesized AlNO films is dependent on oxygen composition and is decreasing in diapason from 1.76 to 2.035 at elevation of the oxygen fraction.It is shown that the AlN films synthesized by pure nitrogen plasma are polycrystalline and textured. The oxygen presence in discharging gas results to growth of amorphous phase of the AlNO film.

The paper presents studies of the structural and optical properties of AlN thin films grown on an AlGaAs/GaAs semiconductor laser heterostructure with the use of preliminary ionic surface cleaning and without it. After cleavage of the heterostructure, a natural surface oxide forms on the facet. In the paper, the ionic etching regime providing the removal of the surface oxide layer without significant defects in the semiconductor heterostructure is determined.

IR and UV spectroscopy is used to study the properties of nanostructured aluminum nitride films obtained via reactive ion-plasma sputtering on GaAs substrates with different orientations. Nanostructured thin (100–200 nm) films of cubic aluminum nitride with optical bandgaps of ~5 eV and refractive indices varying from 1.6 to 4.0 in the wavelength range of ~250 nm are fabricated. Growth on a misoriented GaAs(100) substrate (4° with respect to the [110] plane) makes it possible to synthesize AlN films with smaller grains and higher refractive indices (n ~ 4). It is shown that misoriented GaAs substrates allow us to control the morphology, surface composition, and optical functional characteristics of AlN/GaAs heterophase systems.

Using X-ray diffraction analysis, atomic force microscopy, IR and UV spectroscopy, the properties of thin aluminium nitride films (<200nm) that were obtained by ion-plasma reactive sputtering on GaAs substrates with different orientations were studied.The films of aluminium nitride can have a refractive index within the range of 1.6–4.0 for the wavelength band around ~250nm and an optical band-gap of ~5eV. It was shown that the morphology, surface composition and optical functional characteristics of AlN/GaAs heterophase systems can be controlled owing to the use of misoriented GaAs substrates as well choice of the technological parameters used for the film growth.

The work under consideration presents research of structure, composition and optical properties of aluminium nitride thin films grown by reactive ion plasma sputtering. Aluminium nitride films are shown to contain amorphous and polycrystalline phases. Amorphous phase presence influences on refraction and absorption indexes. Conditions of polycrystalline films with primary (dedicated) orientation synthesis are revealed.