During the operation of lasers based on an AlGaN/InGaN/GaN structure with electron-beam- and optical pumping, a gradual decrease in the output power is observed. In the first minutes of the operation of optical pumping lasers, a certain increase (by 5–10%) in the output power with a successive gradual decrease can be observed. Upon sample cooling, the rate of output-power degradation decreases. A decrease in the output power during operation of the laser is accompanied by changes in the emission spectrum—the line maximum shifts to the short-wavelength region and additional maxima appear. The observed effects can be explained both by the passivation of the initial defects and the diffusion of atoms of the structure during laser operation. The changes in the emission spectra are apparently associated with competition between two different generation channels.

Ultimate Parameters of infrared, visible and blue-violet electron-beam-pumped lasers and laser arrays based on II-VI, III-V and III-N semiconductor heterostructures, obtained at electron energy below ~10keV are discussed.

3rd group element nitride based semiconductor compounds are widely used in various optical and electronic devices. One problem in the fabrication of GaN based device heterostructures is the synthesis of p conductivity epitaxial layers. Magnesium is a typical doping impurity for GaN. The choice of optimum doping and thermal activation conditions is of utmost importance for the synthesis of low-Ohmic p-GaN epitaxial layers. The effect of thermal annealing of GaN:Mg layers on acceptor impurity activation has been investigated. Hole concentration increased and mobility decreased with an increase in thermal annealing temperature. The sample annealed at 1000 °C demonstrated the lowest value of resistivity. Rapid thermal annealing (annealing with high heating speed) considerably improved the efficiency of Mg activation in the GaN layers. The optimum time of annealing at 1000 °C has been determined. The hole concentration increased by up to 4 times compared to specimens after conventional annealing.

We present the results of experimental studies of internal quantum efficiency of photoluminescence of blue LED heterostructures based on multiple InxGa1–xN/GaN quantum wells with short-period InyGa1–yN/GaN superlattices containing small amounts of In at high levels of optical pumping. Introduction of an InyGa1–yN/GaN superlattice from the side of the n-region of a LED InxGa1–xN/GaN heterostructure allows to increase the value of its internal quantum efficiency presumably by reducing the quantum-confined Stark effect and Auger recombination rate.

The parameters of pulsed blue-violet (lambda approximate to 430 nm at T = 300 K) lasers based on an AlGaN/InGaN/GaN structure with five InGaN quantum wells and transverse electron-beam pumping are studied. At room temperature of the active element, the minimum electron energy was 9 keV and the minimum threshold electron beam current density was 8 A cm(-2) at an electron energy of 18 keV.

The results of numerical and experimental study of the electric field strength, photoluminescence wavelength, and internal quantum efficiency of InGaN/GaN (0001) blue LED heterostructures consisting of InGaN multiple quantum wells and GaN barrier layers with the thicknesses of 3, 10, and 15 nm are presented. It is shown that a decrease in the thicknesses of the GaN barrier layers results in a blue shift of the wavelength of LED structures and in an increase of internal quantum efficiency of the structure at high excitation power density.

The results of studies of blue LED InGaN/GaN heterostructures with a short-period InGaN/GaN superlattice in front of an active region of the structure grown on flat and patterned Al2O3 substrates are presented. In these structures, an increase of the internal quantum efficiency is observed. The high-resolution X-ray diffraction spectra and the integrated PL intensity are measured for two temperatures – 10 and 300 K – at different levels of optical YAG-laser pumping.

The results of experimental studies of the dependence of an internal quantum efficiency of blue LED structures with multiple InGaN/GaN quantum wells on the growth temperature of a p-GaN layer are presented. The effect of the magnesium diffusion on the photoluminescence characteristics of LED structures is discussed.

The influence of buffer layers formed at different temperatures and ratios of elements of groups V and III (V/III) on crystalline perfection of epitaxial layers AlN grown using the MOS-Hydride Epitaxy Method on the templates α-Al2O3 is considered. It is shown that the most efficient method to increase the structural perfection of epitaxial layers is use of the high-temperature buffer layer on a low V/III ratio. Further improvement of the quality of AlN layers is possible due to the reduction of parasitic reactions between ammonia and trimethylaluminum in the gas phase by means of optimization of the gas flow through the reactor. The specified values of the growth parameters permitted obtaining the AlN layers of the high crystalline perfection (half-width of X-ray swing curves for reflections (0002), (0004) and \((10\bar 13)\) made asec of 50, 97 and 202, respectively) with a good root-mean-square roughness of the surface of 0.7 nm applicable for the creation of instruments based thereon.

Effect of a patterned sapphire substrate on the increase of external quantum efficiency in “blue” InGaN/GaN LED structures is studied. It is shown that in structures with high internal quantum efficiency (no less than 60%), an increase of the external quantum efficiency is due to an increase of the coefficient of the radiation output from the crystal. Epitaxial growth of GaN on a sapphire substrate with an array of elements of pyramidal shape with a base of 900 nm and a period of 1200 nm allows to increase by 75% the coefficient of the radiation output.

The results of experimental studies of the internal quantum efficiency of blue LED structures with the multiple InGaN / GaN quantum wells and superlattices are discussed.