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The low frequency current and light intensity noise of the next generation light emitting diodes (LEDs) with wavelengths ranging from 265 to 340 nm is reported. The relative spectral noise density of the light intensity fluctuations decreased with an increase of the LED forward current and at high currents, the difference in the noise level for LEDs with different wavelength is small and is of the same order of magnitude or even smaller than for visible LEDs.

The variable stripe length (VSL) method is used to investigate the optical gain in GaN epilayers. Gain peak values up to ~7500 [cm.sup.-1] is shown in GaN epilayers grown on AIN buffer layers deposited on sapphire by migration enhanced metal-organic chemical vapor deposition.

Low frequency noise was investigated in GaN metal semiconductor and metal oxide semiconductor field effect transistors.

Gate leakage current effects on noise in A1GaN/GaN field effect transistors are examined.

A new study investigates low-frequency noise in gallium nitride/gallium-aluminum nitride field effect transistors grown on silicon carbide and sapphire substrates.

Research was conducted to examine the low-frequency noise-characteristics and performance of visible-blind GaN p-n junction photodetectors. Hopping via defect-related states in the depletion region, which was believed to be associated with dislocations, was identified as the dominant current mechanism. Results obtained under reverse bias, under forward bias and under illumination are presented.

Monte Carlo simulation studies of hot-electron relaxation properties in rectangular GaAs quantum wires reveal that optical phonon emission defines initial excitation energy-dependent hot-electron cooling. Inelastic interactions between electrons and acoustic and optical phonons control the slow relaxation stage. The influence of hot phonons on electrons depends on energy distribution of electrons.

The spectral dependences of the nonequilibrium carrier lifetimes obtained by using time-resolved photoluminescence (PL) spectroscopy reveal new features in the carrier dynamics in AlGaN epilayers with high aluminum content. Three decay components can be traced in the PL decay. The fast, intermediate, and slow components are attributed to the decay of the free carriers, localized carriers, and the carriers trapped in deep states, respectively. The spectral dependence of the fast component is flat with a very weak dependence on temperature. At low temperatures, the intermediate decay component has the longest effective decay times in the vicinity of the PL band peak and exhibits a decrease on both high and low energy slopes. The spectral dependence of the lifetimes flattens at elevated temperatures. To interpret the decrease in the carrier lifetime at lower energies, we suggest the modification of the double-scaled potential profile in AlGaN alloys by introducing a gradual potential decrease to the low-potential regions instead of the abrupt walls of the regions previously assumed. [ABSTRACT FROM AUTHOR]

A strong piezoresistive effect was detected in AlN-GaN shrot-range superlattices. The measured static gauge factor ranged from 30 to about 90 depending on the superlattice composition. These values were much bigger than the values of the gauge factor reported for GaN-AlN-GaN semiconductor-insulator-semiconductor structures. Findings illustrate a strong potential for AlN-GaN-based materials for the development of piezoelectric and piezoresistive sensors.

A double-channel AlGaN/GaN heterostructure field-effect transistor (HFET) was proposed for high power applications, where the bottom channel was formed by a GaN/AlGaN/GaN semiconductor-insulator-semiconductor structure. Charge distribution and the band structure were strongly affected by the piezoelectric effect caused by the mismatch between AlGaN and GaN. This design demonstrated that the carrying capability of AlGaN/GaN HFETs can be enhanced using multichannel structures.