We report on the fabrication of 280-nm AlGaN-based deep-ultraviolet light-emitting diodes sUV LEDsd on sapphire substrates with an integrated microlens array. Microlenses with a diameter of 12 mm 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 submounts to improve the thermal diss...

The interface formation mechanisms of AlN films on sapphire substrates grown by the elementary source vapor phase epitaxy (EVPE) method, which is a new AlN bulk fabrication method using Al and N2 as precursors, are investigated. Supplying N2 after the substrate temperature reaches the growth temperature [Process N2(GT)] causes the interface to become rough due to the thermal decomposition of sa...

In this work, the position-controlled growth of GaN nanowires on sapphire wafers and on N-polar GaN templates is presented using selective area vapor-liquid-solid growth in a metalorganic vapor phase reactor. Misoriented sapphire wafers and TMIn acting as surfactant are applied in order to achieve N-polar GaN buffer layers with high crystal and surface quality, suitable for a subsequent nano-pa...

GaN-based light emitting diodes (LEDs) fabricated on sapphire substrates were successfully transferred onto silicon substrates using a double-transfer technique. Compared with the conventional LEDs on sapphire, the transferred LEDs showed a significant improvement in the light extraction and thermal dissipation, which should be mainly attributed to the removal of sapphire and the good thermal c...

Sapphire single crystal [a-Al2O3(0 0 0 1)] samples were treated by irradiation with Ti‡ ions in the energy range 0.5±7.0 keV at 25°C and 750°C under UHV conditions for total doses of 10 Ti‡/cm2. These Ti treated sapphire samples were studied by ex situ X-ray photoelectron spectroscopy (XPS) depth pro®ling and by atomic force microscopy (AFM). Aluminum in the oxidation states Al0;3‡;x‡, where 0 ...

Experimental study on slicing of sapphire with fixed abrasive diamond wire saw was conducted in this paper. The process parameters were optimized through orthogonal experiment of three factors and four levels. The effects of wire speed, feed speed and tension pressure on the surface roughness were analyzed. Surface roughness in cutting direction and feed direction were both detected. The result...

Nanopatterned aluminum nitride (NP-AlN) templates were used to enhance the light extraction efficiency of the light-emitting diodes (LEDs). Here, the NP-AlN interlayer between the sapphire substrate and GaN-based LED was used as an effective light outcoupling layer at the direction of bottom side and as a buffer layer for growth of GaN LEDs. The cross-sectional transmission electron microscopy ...