Results of a deep‐level transient spectroscopy (DLTS) study of trapping states in Ni/Au Schottky diodes made on Si‐doped GaN layers grown by metal–organic vapor‐phase epitaxy (MOVPE) on highly conductive n‐type Ammono‐GaN substrates are reported. In all as‐grown samples, the DLTS signals due to traps with the activation energies for electron emission (Eem) of about 0.26 and 0.60 eV (referred to as E1 and E3 traps, respectively) have been detected. It is found that the electric field (E) significantly enhances the electron emission rate (eem) for the E1 trap, while for the E3 trap the eem(E) dependence is not very strong. The eem(E) dependence for the E1 trap is found to be characteristic of attractive traps with spherically symmetric square well potential with a radius of about 2.9 ± 0.25 nm. The eem(E) dependence for the E3 trap is accounted for by a phonon‐assisted tunneling mechanism. The zero‐E Eem values for both traps are determined. Correlations between the concentrations of the E1 and E3 traps and concentrations of impurities (H, C, Si, O, Mg, and Fe) determined by secondary ion mass spectrometry in the samples are investigated. Charge states and origins of the E1 and E3 traps are discussed.

The present paper focuses on the high-pressure metal-organic vapor phase epitaxy (MOVPE) upside-down vertical reactor (where the inlet of cold gases is below a hot susceptor). This study aims to investigate thermo-kinetic phenomena taking place during the GaN (gallium nitride) growth process using trimethylgallium and ammonia at a pressure of above 2 bar. High pressure accelerates the growth process, but it results in poor thickness and quality in the obtained layers; hence, understanding the factors influencing non-uniformity is crucial. The present investigations have been conducted with the aid of ANSYS Fluent finite volume method commercial software. The obtained results confirm the possibility of increasing the growth rate by more than six times through increasing the pressure from 0.5 bar to 2.5 bar. The analysis shows which zones vortexes form in. Special attention should be paid to the transitional flow within the growth zone as well as the viewport. Furthermore, the normal reactor design cannot be used under the considered conditions, even for the lower pressure value of 0.5 bar, due to high turbulences.

Secondary ion mass spectrometry measurements can provide specific information on In fluctuations in InGaN quantum wells.

InGaN/GaN multiple quantum well structures were grown on bulk GaN and on sapphire substrates using the metalorganic vapor-phase epitaxy in order to study the influence of hydrogen during the growth of the GaN barriers. This hydrogen flow had the following effects on the structures: (i) the thickness of the QWs was reduced, (ii) the indium concentration in the QWs was decreased and (iii) the growth rate of the quantum barriers was increased.

The InGaN layers were grown using the Metalorganic Vapour Phase Epitaxy on bulk GaN substrates in a stop-and-go-mode (30 s growth, 30 s stop) and then examined using X-ray Diffraction (XRD), Photoluminescence (PL), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). The experiment was done in order to study an influence of hydrogen and TMIn flows during the growth-breaks on the InGaN layer. It was found that the presence of hydrogen during the breaks removes indium atoms from the already grown InGaN layer and delays In-incorporation into the subsequent one. As a result, instead of having about 18% of In in the continuously grown InGaN, we have only about 6% (average In-content) and the layer is thinner by more than 20%. In the case of having simultaneously H2 and TMIn flows on during the breaks, we get three times less of In-atoms torn away and the layer has the thickness unchanged. The simultaneous presence of TMIn and H2 also gave much smaller surface roughness as compared to the situation when only H2 was on during the breaks.

So far, most of the SiC homoepitaxy has been realized on 8-deg-off and 4-deg-off substrates, whereas GaN heteroepitaxy is done on SiC on-axis (up to 0.3 deg off). As 6-inch SiC wafers are being introduced into the market, a decrease of the substrate off-cut to 2 deg for SiC homoepitaxy is desirable to reduce the manufacturing costs. If both, GaN heteroepitaxy and SiC homoepitaxy are successful on 2-deg-off SiC substrates, this would pave the way to monolithic integration of both kinds of devices, as well as to obtain cheap insulating SiC substrates for AlGaN/GaN microwave and THz devices. In this work, we present our present status of AlGaN/GaN growth on SiC 2-deg off. Comparing to the on-axis situation, we obtained similar structural (XRD and TEM data) and electrical characteristics, but not morphological ones. Therefore, we propose two ways of a decrease of AlGaN surface roughness when grown on SiC 2 deg-off: i) by planarization, ii) by lateral patterning.

A patterned GaN/sapphire template with separate regions angled between 0.4 and 2° to the wurtzite c-plane was used to grow a 50 nm In0.1Ga0.9N layer. The photoluminescence wavelength varied between 403 and 389 nm according to the increased region's angle. The indium content measured using X-rays was reduced in regions with a higher miscut angle. Patterned freestanding GaN with separate regions angled by 0.35 and 0.85° to the c-plane was used to fabricate ridge-waveguide diode lasers. Each laser stripe was placed inside one of the angled regions. Lasing wavelengths of 405.8±0.2 and 401.0±1 nm were obtained for devices grown in those regions.