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A fractal-percolation system that includes extended defects and random fluctuations in the alloy composition is formed during the growth of device structures based on Group-III nitrides. It is established that the specific features of this system are determined not only by the growth conditions. It is shown that the diversity of the electrical and optical properties of InGaN/GaN LEDs (light-emitting diodes) emitting at wavelengths of 450-460 and 519-530 nm, as well as that of the electrical properties of AlGaN/GaN HEMT (high-electron-mobility transistor) structures, is due to modification of the properties of the fractal-percolation system both during the growth process and under the action of the injection current and irradiation. The influence exerted by these specific features on the service life of light-emitting devices and on the reliability of AlGaN/GaN HEMT structures is discussed. [ABSTRACT FROM AUTHOR]

Double heterostructures AlGaN/GaN/AlGaN grown by hydride vapor phase epitaxy and designed for use as light emitting diodes for 360 nm wavelength were patterned by shallow nanoholes and injected with Ag/SiO2 or Al nanoparticles. A 1.8 times increase in the photoluminescence and microcathodoluminescence signal from the GaN active region was observed for 100 nm diameter Al nanoparticles, the efficiency decreased compared to the reference planar samples for small Al nanoparticles of 30-40 nm diameter, and a moderate increase of 1.2 times was detected for Ag/SiO2 nanoparticles. The observed phenomena are explained by the GaN emitter coupling with localized surface plasmons produced by metallic nanoparticles. (© 2015 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Blue light-emitting diodes (LEDs) based on InGaN/GaN quantum wells (QWs) with different characters of the system of extended defects (SEDs) threading through the active region have been studied using the current-voltage ( I–U), capacitance-voltage ( C–V), and deep-level transient spectroscopy (DLTS) measurements in the dark and under illumination with white light in a temperature range from 100 to 450 K. The DLTS curves exhibit broad E1 and E2 peaks with amplitudes dependent on the illumination. This behavior can be explained assuming the presence of localized states related to SEDs in the active region of the LED. The LEDs with more developed SEDs are characterized by a greater concentration of donor-type traps, which leads to an increase in the density of free charge carriers in QWs, which screen the electron-hole interaction. This circumstance can be among the factors responsible for a severalfold decrease in the quantum efficiency of such LEDs. [ABSTRACT FROM AUTHOR]

An investigation was made of the electrochemical etching of i-n-GaN light-emitting diode structures in aqueous solutions of KOH and NaOH to remove parasitic low-resistivity layers and inclusions in the structures which shunt the active current flow channels through the structures and lower the electroluminescence intensity. The electroluminescence intensity of the structures increased by two or three orders of magnitude during the etching process. [ABSTRACT FROM AUTHOR]