Abstract: A method for growing III-V nitride films having an N-face or M-plane using an ammonothermal growth technique. The method comprises using an autoclave, heating the autoclave, and introducing ammonia into the autoclave to produce smooth N-face or M-plane Gallium Nitride films and bulk GaN.

Abstract: A method of growing group III-nitride crystals in a mixture of supercritical ammonia and nitrogen, and the group-III crystals grown by this method. The group III-nitride crystal is grown in a reaction vessel in supercritical ammonia using a source material or nutrient that is polycrystalline group III-nitride, amorphous group III-nitride, group-III metal or a mixture of the above, and a seed crystal that is a group-III nitride single crystal. In order to grow high-quality group III-nitride crystals, the crystallization temperature is set at 550° C. or higher. Theoretical calculations show that dissociation of NH3 at this temperature is significant. However, the dissociation of NH3 is avoided by adding extra N2 pressure after filling the reaction vessel with NH3.

Abstract: A method for growing III-V nitride films having an N-face or M-plane using an ammonothermal growth technique. The method comprises using an autoclave, heating the autoclave, and introducing ammonia into the autoclave to produce smooth N-face or M-plane Gallium Nitride films and bulk GaN.

Abstract: The present invention discloses methods to produce large quantities of polycrystalline GaN for use in the ammonothermal growth of group III-nitride material. High production rates of GaN can be produced in a hydride vapor phase growth system. One drawback to enhanced polycrystalline growth is the increased incorporation of impurities, such as oxygen. A new reactor design using non-oxide material that reduces impurity concentrations is disclosed. Purification of remaining source material after an ammonothermal growth is also disclosed. The methods described produce sufficient quantities of polycrystalline GaN source material for the ammonothermal growth of group III-nitride material.

Abstract: The present disclosure proves for new design of reactors used for ammonothermal growth of III nitride crystals. The reactors include a region intermediate a source dissolution region and a crystal growth region configured to provide growth of high quality crystals at rates greater than 100 ?m/day. In one embodiment, multiple baffle plates having openings whose location is designed so that there is no direct path through the intermediate region, or with multiple baffle plates having differently sized openings on each plate so that the flow is slowed down and/or exhibit greater mixing are described. The disclosed designs enables obtaining high temperature difference between the dissolution region and the crystallization region without decreasing conductance through the device.

Abstract: The present invention discloses a high-pressure vessel of large size formed with a limited size of e.g. Ni—Cr based precipitation hardenable superalloy. The vessel may have multiple zones. For instance, the high-pressure vessel may be divided into at least three regions with flow-restricting devices and the crystallization region is set higher temperature than other regions. This structure helps to reliably seal both ends of the high-pressure vessel, and at the same time, may help to greatly reduce unfavorable precipitation of group III nitride at the bottom of the vessel. This invention also discloses novel procedures to grow crystals with improved purity, transparency and structural quality. Alkali metal-containing mineralizers are charged with minimum exposure to oxygen and moisture until the high-pressure vessel is filled with ammonia. Several methods to reduce oxygen contamination during the process steps are presented.

Abstract: The present invention discloses a new testing method of group III-nitride wafers. By utilizing the ammonothermal method, GaN or other Group III-nitride wafers can be obtained by slicing the bulk GaN ingots. Since these wafers originate from the same ingot, these wafers have similar properties/qualities. Therefore, properties of wafers sliced from an ingot can be estimated from measurement data obtained from selected number of wafers sliced from the same ingot or an ingot before slicing. These estimated properties can be used for product certificate of untested wafers. This scheme can reduce a significant amount of time, labor and cost related to quality control.

Abstract: The present invention discloses methods to create higher quality group III-nitride wafers that then generate improvements in the crystalline properties of ingots produced by ammonothermal growth from an initial defective seed. By obtaining future seeds from carefully chosen regions of an ingot produced on a bowed seed crystal, future ingot crystalline properties can be improved. Specifically, the future seeds are optimized if chosen from an area of relieved stress on a cracked ingot or from a carefully chosen N-polar compressed area. When the seeds are sliced out, miscut of 3-10° helps to improve structural quality of successive growth. Additionally a method is proposed to improve crystal quality by using the ammonothermal method to produce a series of ingots, each using a specifically oriented seed from the previous ingot. When employed, these methods enhance the quality of Group III nitride wafers and thus improve the efficiency of any subsequent device.

Abstract: The present invention discloses a production method for group III nitride ingots or pieces such as wafers. To solve the coloration problem in the wafers grown by the ammonothermal method, the present invention composed of the following steps; growth of group III nitride ingots by the ammonothermal method, slicing of the ingots into wafers, annealing of the wafers in a manner that avoids dissociation or decomposition of the wafers. This annealing process is effective to improve transparency of the wafers and/or otherwise remove contaminants from wafers.

Abstract: A gallium nitride crystal with a polyhedron shape having exposed {10-10} m-planes and an exposed (000-1) N-polar c-plane, wherein a surface area of the exposed (000-1) N-polar c-plane is more than 10 mm2 and a total surface area of the exposed {10-10} m-planes is larger than half of the surface area of (000-1) N-polar c-plane. The GaN bulk crystals were grown by an ammonothermal method with a higher temperature and temperature difference than is used conventionally, and using an autoclave having a high-pressure vessel with an upper region and a lower region. The temperature of the lower region of the high-pressure vessel is at or above 550° C., the temperature of the upper region of the high-pressure vessel is set at or above 500° C., and the temperature difference between the lower and upper regions is maintained at or above 30° C. GaN seed crystals having a longest dimension along the c-axis and exposed large area m-planes are used.

Abstract: A method of growing group III-nitride crystals in a mixture of supercritical ammonia and nitrogen, and the group-III crystals grown by this method. The group III-nitride crystal is grown in a reaction vessel in supercritical ammonia using a source material or nutrient that is polycrystalline group III-nitride, amorphous group III-nitride, group-III metal or a mixture of the above, and a seed crystal that is a group-III nitride single crystal. In order to grow high-quality group III-nitride crystals, the crystallization temperature is set at 550° C. or higher. Theoretical calculations show that dissociation of NH3 at this temperature is significant. However, the dissociation of NH3 is avoided by adding extra N2 pressure after filling the reaction vessel with NH3.

Abstract: A method for growing III-nitride films containing aluminum using Hydride Vapor Phase Epitaxy (HVPE) is disclosed, and comprises using corrosion-resistant materials in an HVPE system, the region of the HVPE system containing the corrosion-resistant materials being an area that contacts an aluminum halide, heating a source zone with an aluminum-containing source above a predetermined temperature, and growing the III-nitride film containing aluminum within the HVPE system containing the corrosion-resistant material.

Abstract: A method for growing III-V nitride films having an N-face or M-plane using an ammonothermal growth technique. The method comprises using an autoclave, heating the autoclave, and introducing ammonia into the autoclave to produce smooth N-face or M-plane Gallium Nitride films and bulk GaN.

Abstract: A method for growing gallium nitride (GaN) crystals in supercritical ammonia using an autoclave is disclosed. Large surface area GaN crystals are created, which may include calcium, magnesium or vanadium or less than 1% indium.

Abstract: A personal handyphone system performing radio connection using a time division multiple access (TDMA)-time division duplex (TDD) system includes a mobile station which includes means for performing carrier sensing of a communication frequency designated by a base station and a reception slot, and means for performing carrier sensing of a transmission slot.

Abstract: A sapphire substrate, a buffer layer of undoped GaN and a compound semiconductor crystal layer successively formed on the sapphire substrate together form a substrate of a light emitting diode. A first cladding layer of n-type GaN, an active layer of undoped In0.2Ga0.8N and a second cladding layer successively formed on the compound semiconductor crystal layer together form a device structure of the light emitting diode. On the second cladding layer, a p-type electrode is formed, and on the first cladding layer, an n-type electrode is formed. In a part of the sapphire substrate opposing the p-type electrode, a recess having a trapezoidal section is formed, so that the thickness of an upper portion of the sapphire substrate above the recess can be substantially equal to or smaller than the thickness of the compound semiconductor crystal layer.

Abstract: A radio communication method includes (a) providing a mobile station and (b) changing a period. The mobile station can make a call through each of an independent system base station and an outdoor public system base station. The period is a period when a waiting operation to the independent system base station is performed. The period is changed based on a distance between the mobile station and the independent system base station.

Abstract: A method for growing a nitride compound semiconductor according to the present invention includes the step of growing a compound semiconductor expressed by a general formula AlxGa1-xN (where 0≦×≦1) on a nitride compound semiconductor substrate at a temperature of about 900° C. or more.

Abstract: The nitride semiconductor laser device of the present invention includes: a nitride semiconductor laser diode; and a protective layer formed on at least one facet of the nitride semiconductor laser diode. The protective layer is made of Al1-x-y-zGaxInyBaN (where 0≦x, y, z≦1 and 0≦x+y+z≦1), which is transparent to light emitted from the laser diode.

Abstract: A sapphire substrate, a buffer layer of undoped GaN and a compound semiconductor crystal layer successively formed on the sapphire substrate together form a substrate of a light emitting diode. A first cladding layer of n-type GaN, an active layer of undoped In.sub.0.2 Ga.sub.0.8 N and a second cladding layer successively formed on the compound semiconductor crystal layer together form a device structure of the light emitting diode. On the second cladding layer, a p-type electrode is formed, and on the first cladding layer, an n-type electrode is formed. In a part of the sapphire substrate opposing the p-type electrode, a recess having a trapezoidal section is formed, so that the thickness of an upper portion of the sapphire substrate above the recess can be substantially equal to or smaller than the thickness of the compound semiconductor crystal layer.