Abstract: The present invention discloses an electronic device formed of a group III nitride. In one embodiment, a substrate is fabricated by the ammonothermal method and a drift layer is fabricated by hydride vapor phase epitaxy. After etching a trench, p-type contact pads are made by pulsed laser deposition followed by n-type contact pads by pulsed laser deposition. The bandgap of the p-type contact pad is designed larger than that of the drift layer. Upon forward bias between p-type contact pads (gate) and n-type contact pads (source), holes and electrons are injected into the drift layer from the p-type contact pads and n-type contact pads. Injected electrons drift to the backside of the substrate (drain).

Abstract: The present invention discloses an electronic device formed of a group III nitride. In one embodiment, a substrate is fabricated by the ammonothermal method and a drift layer is fabricated by hydride vapor phase epitaxy. After etching a trench, p-type contact pads are made by pulsed laser deposition followed by n-type contact pads by pulsed laser deposition. The bandgap of the p-type contact pad is designed larger than that of the drift layer. Upon forward bias between p-type contact pads (gate) and n-type contact pads (source), holes and electrons are injected into the drift layer from the p-type contact pads and n-type contact pads. Injected electrons drift to the backside of the substrate (drain).

Abstract: Present invention discloses a high-pressure vessel of large size formed with a limited size of e.g. Ni—Cr based precipitation hardenable superalloy. 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, at the same time, may help to greatly reduce unfavorable precipitation of group III nitride at the bottom of the vessel. 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 invention provides, in one instance, a group III nitride wafer sliced from a group III nitride ingot, polished to remove the surface damage layer and tested with x-ray diffraction. The x-ray incident beam is irradiated at an angle less than 15 degree and diffraction peak intensity is evaluated. The group III nitride wafer passing this test has sufficient surface quality for device fabrication. The invention also provides, in one instance, a method of producing group III nitride wafer by slicing a group III nitride ingot, polishing at least one surface of the wafer, and testing the surface quality with x-ray diffraction having an incident beam angle less than 15 degree to the surface. The invention also provides, in an instance, a test method for testing the surface quality of group III nitride wafers using x-ray diffraction having an incident beam angle less than 15 degree to the surface.

Abstract: The present invention discloses an electronic device formed of a group III nitride. In one embodiment, a substrate is fabricated by the ammonothermal method and a drift layer is fabricated by hydride vapor phase epitaxy. After etching a trench, p-type contact pads are made by pulsed laser deposition followed by n-type contact pads by pulsed laser deposition. The bandgap of the p-type contact pad is designed larger than that of the drift layer. Upon forward bias between p-type contact pads (gate) and n-type contact pads (source), holes and electrons are injected into the drift layer from the p-type contact pads and n-type contact pads. Injected electrons drift to the backside of the substrate (drain).

Abstract: The present invention discloses an electronic device formed of a group III nitride. In one embodiment, a substrate is fabricated by the ammonothermal method and a drift layer is fabricated by hydride vapor phase epitaxy. After etching a trench, p-type contact pads are made by pulsed laser deposition followed by n-type contact pads by pulsed laser deposition. The bandgap of the p-type contact pad is designed larger than that of the drift layer. Upon forward bias between p-type contact pads (gate) and n-type contact pads (source), holes and electrons are injected into the drift layer from the p-type contact pads and n-type contact pads. Injected electrons drift to the backside of the substrate (drain).

Abstract: The present invention discloses an electronic device formed of a group III nitride. In one embodiment, a substrate is fabricated by the ammonothermal method and a drift layer is fabricated by hydride vapor phase epitaxy. After etching a trench, p-type contact pads are made by pulsed laser deposition followed by n-type contact pads by pulsed laser deposition. The bandgap of the p-type contact pad is designed larger than that of the drift layer. Upon forward bias between p-type contact pads (gate) and n-type contact pads (source), holes and electrons are injected into the drift layer from the p-type contact pads and n-type contact pads. Injected electrons drift to the backside of the substrate (drain).

Abstract: The present invention discloses an electronic device formed of a group III nitride. In one embodiment, a substrate is fabricated by the ammonothermal method and a drift layer is fabricated by hydride vapor phase epitaxy. After etching a trench, p-type contact pads are made by pulsed laser deposition followed by n-type contact pads by pulsed laser deposition. The bandgap of the p-type contact pad is designed larger than that of the drift layer. Upon forward bias between p-type contact pads (gate) and n-type contact pads (source), holes and electrons are injected into the drift layer from the p-type contact pads and n-type contact pads. Injected electrons drift to the backside of the substrate (drain).

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: In one instance, the invention provides a method of growing bulk crystal of group III nitride using a seed crystal selected by (a) measuring x-ray rocking curves of a seed crystal at more than one point, (b) quantifying the peak widths of the measured x-ray rocking curves, and (c) evaluating the distribution of the quantified peak widths. The invention also includes the method of selecting a seed crystal for growing bulk crystal of group III nitride. The bulk crystal of group III nitride can be grown in supercritical ammonia or a melt of group III metal using at least one seed selected by the method above.

Abstract: Provided is a high-pressure reactor suitable for a high-pressure process using supercritical ammonia grow bulk crystal of group III nitride having lateral dimension larger than 2 inches or to form various transition metal nitrides. The reactor has nutrient distributed along the reactor's longitudinal axis and seed material positioned at the reactor's inner wall and along the reactor's longitudinal axis. Nutrient diffuses through supercritical ammonia from the reactor's longitudinal axis and deposits on the seed material positioned by the reactor's inner wall. Both the nutrient and seed material are heated by the same heater. Material growth can primarily be due to material diffusion through supercritical ammonia. This configuration and methodology reduce convective movement of supercritical ammonia due to temperature differential, providing a more quiescent environment in which group III nitride or transition metal nitride is formed.

Abstract: Bulk crystal of group III nitride having thickness greater than 1 mm with improved crystal quality, reduced lattice bowing and/or reduced crack density and methods of making. Bulk crystal has a seed crystal, a first crystalline portion grown on the first side of the seed crystal and a second crystalline portion grown on the second side of the seed crystal. Either or both crystalline portions have an electron concentration and/or an oxygen concentration similar to the seed crystal. The bulk crystal can have an additional seed crystal, with common faces (e.g. same polarity, same crystal plane) of seed crystals joined so that a first crystalline part grows on the first face of the first seed crystal and a second crystalline part grows on the first face of the second seed crystal. Each crystalline part's electron concentration and/or oxygen concentration may be similar to its corresponding seed crystal.

Abstract: In one instance, the invention provides a group III nitride crystal having a first side exposing nitrogen polar c-plane of single crystalline or highly oriented polycrystalline group III nitride and a second side exposing group III polar surface, polycrystalline phase, or amorphous phase of group III nitride. Such structure is useful as a seed crystal for ammonothermal growth of bulk group III nitride crystals. The invention also discloses the method of fabricating such crystal. The invention also discloses the method of fabricating a bulk crystal of group III nitride by ammonothermal method using such crystal.

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: In one instance, the invention provides a group III nitride crystal having a first side exposing nitrogen polar c-plane of single crystalline or highly oriented polycrystalline group III nitride and a second side exposing group III polar surface, polycrystalline phase, or amorphous phase of group III nitride. Such structure is useful as a seed crystal for ammonothermal growth of bulk group III nitride crystals. The invention also discloses the method of fabricating such crystal. The invention also discloses the method of fabricating a bulk crystal of group III nitride by ammonothermal method using such crystal.

Abstract: In one instance, the invention provides a bulk crystal of group III nitride having a thickness of more than 1 mm without cracking above the sides of a seed crystal. This bulk group III nitride crystal is expressed as Gax1Aly1In1-x1-y1N (0?x1?1, 0?x1+y1?1) and the seed crystal is expressed as Gax2Aly2In1-x2-y2N (0?x2?1, 0?x2+y2?1). The bulk crystal of group III nitride can be grown in supercritical ammonia or a melt of group III metal using at least one seed crystal having basal planes of c-orientation and sidewalls of m-orientation. By exposing only c-planes and m-planes in this instance, cracks originating from the sides of the seed crystal are avoided.

Abstract: Provided is a high-pressure reactor suitable for a high-pressure process using supercritical ammonia grow bulk crystal of group III nitride having lateral dimension larger than 2 inches or to form various transition metal nitrides. The reactor has nutrient distributed along the reactor's longitudinal axis and seed material positioned at the reactor's inner wall and along the reactor's longitudinal axis. Nutrient diffuses through supercritical ammonia from the reactor's longitudinal axis and deposits on the seed material positioned by the reactor's inner wall. Both the nutrient and seed material are heated by the same heater. Material growth can primarily be due to material diffusion through supercritical ammonia. This configuration and methodology reduce convective movement of supercritical ammonia due to temperature differential, providing a more quiescent environment in which group III nitride or transition metal nitride is formed.

Abstract: Group III nitride substrate having a first side of nonpolar or semipolar plane and a second side has more than one stripe of metal buried, wherein the stripes are perpendicular to group III nitride's c-axis. More than 90% of stacking faults exist over metal stripes. Second side may expose a nonpolar or semipolar plane. Also disclosed is a group III nitride substrate having a first side of nonpolar or semipolar plane and a second side with exposed nonpolar or semipolar plane. The substrate contains bundles of stacking faults with spacing larger than 1 mm. The invention also provides methods of fabricating the group III nitride substrates above.

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 method of removing contaminant from group III nitride single-crystal wafers. The method involves annealing a wafer to concentrate a contaminant in a region of the crystal near the surface of the crystal and removing some of the crystal near the surface that contains at least a portion of the region containing concentrated contaminant. The resultant thinner wafer therefore has less contaminant in it.