Light-emitting device, method of fabricating the device, and LED lamp using the device
A technology of light-emitting elements and manufacturing methods, applied in semiconductor/solid-state device manufacturing, electrical components, semiconductor devices, etc., to achieve the effect of improving the extraction effect
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Embodiment 1
[0052] In Example 1, a sapphire substrate having a (0001) surface was used. By applying pure water on sandpaper coated with a diamond-like abrasive and rubbing it while moving in the direction of the sapphire substrate, it is formed in a linear shape approximately along the direction Concave-convex structure. The cross-sectional shape of the concave portion observed by SEM was a triangular shape (V-shaped groove shape) with a width of 1 μm and a depth of 0.5 μm. The angle θ formed by the uphill slope of the V-shaped groove and the substrate plane is approximately in the range of 30° to 60° around 45°. When observed with an optical microscope at magnification of 600, the ratio of the area of the flat portion to the area of the scratched portion was 2:1 on average.
[0053] The thus-fabricated sapphire substrate with V-shaped grooves was thoroughly cleaned and put into an MOCVD apparatus. Then, as the first step, a process of flowing a mixed gas containing trimethylalum...
Embodiment 2
[0091] In Example 2, a sapphire substrate with a 1 μm-thick AlN film whose surface is a (0001) plane was used. By subjecting the substrate to a high-temperature treatment at 1400° C. in a reducing atmosphere, hexagonal pyramid pits and irregular-shaped irregularities were formed on the AlN surface. The diameter of the pit is about 0.5 to 2 μm, and the bottom surface of the larger one reaches the sapphire substrate, and some of them form a hexagonal pyramid shape. The ratio of the area occupied by the pits and irregular-shaped unevenness to the area of the flat portion is about 1:0.2 to 1:4. The slope of the hexagonal pyramid is composed of two types of AlN (11-22) plane and (1-102) plane, and the angle θ formed by the slope of the hexagonal pyramid and the substrate plane is 58° and 43°, respectively.
[0092] The sapphire substrate with the AlN film on which the pits formed in this way was fully cleaned, put into an MOCVD apparatus, and an epitaxial wafer for LEDs was prod...
Embodiment 3
[0096] In Example 3, a sapphire substrate having a (0001) surface was used. A selective growth mask made of a stripe-shaped SiN film with a line width of 2 μm and a space width of 2 μm was formed parallel to the direction of the sapphire on the substrate, and it was fully cleaned and put into an MOCVD apparatus. Then, as a first step, a gas containing trimethylaluminum (TMAl) vapor was flowed at high temperature, and as a second step, TMAl and ammonia were flowed to grow striped aluminum nitride with a triangular cross section. Furthermore, the LED structure is then fabricated after planarizing it with gallium nitride.
[0097] The above-mentioned samples including the AlN layer were fabricated by MOCVD in the following steps. First, a sapphire substrate was introduced into a reaction furnace made of quartz installed in an RF coil of an induction heating heater. The sapphire substrate was placed on a carbon susceptor for heating inside a spherical box substituted with nitro...
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