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We present results on enhancement of 460 nm blue and 340 nm UV optical power output in III-nitride light emitting diodes ͑LEDs͒ using photonic crystals ͑PCs͒ under current injection. Triangular arrays of the PCs with diameter/periodicity of 300/700 nm were patterned using electron-beam lithography and inductively coupled plasma dry etching. The total power(More)
We report on the fabrication and photovoltaic characteristics of InGaN solar cells by exploiting InGaN/GaN multiple quantum wells ͑MQWs͒ with In contents exceeding 0.3, attempting to alleviate to a certain degree the phase separation issue and demonstrate solar cell operation at wavelengths longer than previous attainments ͑Ͼ420 nm͒. The fabricated solar(More)
Deep UV photoluminescence spectroscopy has been employed to study the optical properties of Al x Ga 1−x N alloys ͑0 ഛ x ഛ 1͒. The emission intensity with polarization of E Ќ c and the degree of polarization were found to decrease with increasing x. This is a consequence of the fact that the dominant band edge emission in GaN ͑AlN͒ is with polarization of E(More)
Refractive indices of Al x Ga 1Ϫx N with different Al concentrations have been measured in infrared wavelength regions. Single-mode ridged optical waveguide devices using GaN/AlGaN heterostructures have been designed, fabricated, and characterized for operation in 1550 nm wavelength window. The feasibility of developing photonic integrated circuits based on(More)
We report on the fabrication of 280-nm AlGaN-based deep-ultraviolet light-emitting diodes ͑UV LEDs͒ on sapphire substrates with an integrated microlens array. Microlenses with a diameter of 12 ␮m were fabricated on the sapphire substrate by resist thermal reflow and plasma dry etching. LED devices were flip-chip bonded on high thermal conductive AlN ceramic(More)
III-nitride photonic crystal ͑PC͒ ultraviolet ͑UV͒ light-emitting diodes ͑LEDs͒ were fabricated. Triangular arrays of the PCs with different diameters/periodicities were patterned using electron-beam lithography and inductively coupled plasma dry etching. The optical power output of LEDs was enhanced by a factor of 2.5 due to PC formation. It was observed(More)
Deep ultraviolet ͑DUV͒ avalanche photodetectors ͑APDs͒ based on an AlN / n-SiC Schottky diode structure have been demonstrated. The device with a mesa diameter of ϳ100 ␮m exhibits a gain of 1200 at a reverse bias voltage of −250 V or a field of about 3 MV/ cm. The cutoff and peak responsivity wavelengths of these APDs were 210 and 200 nm, respectively. This(More)
We have observed for the first time conductivity fluctuations in the persistent photoconductivity mode in II-VI mixed crystals with the magnitude following the percolation approach as ~ T — T, ~ s, where T, is the percolation threshold temperature. Experimental results have demonstrated that the random local-potential fluctuations induced by compositional(More)