A silicon carbide ingot is provided, which includes a seed end, and a dome end opposite to the seed end. In the silicon carbide ingot, a ratio of the vanadium concentration to the nitrogen concentration at the seed end is in a range of 5:1 to 11:1, and a ratio of the vanadium concentration to the nitrogen concentration at the dome end is in a range of 2:1 to 11:1.

Provided are: a silicon carbide single crystal substrate which is cut out from a silicon carbide bulk single crystal grown by the Physical Vapor Transport method; and a process for producing the same. The number of screw dislocations in one of the semicircle areas of the substrate is smaller than that in the other thereof, namely, the number of screw dislocations in a given area of the substrate is reduced. The semicircle areas of the substrate correspond respectively to the halves of the substrate. The present invention pertains to: a silicon carbide single crystal substrate which is cut out from a silicon carbide bulk single crystal grown by the Physical Vapor Transport method and which is characterized in that the average value of the screw-dislocation densities observed at multiple measurement points in one of the semicircle areas, which correspond respectively to the halves of the substrate, is 80% or less of the average value of screw-dislocation densities observed at multiple measurement points in the other of the semicircle areas; and a process for producing the same.

In various embodiments, non-zero thermal gradients are formed within a growth chamber both substantially parallel and substantially perpendicular to the growth direction during formation of semiconductor crystals, where the ratio of the two thermal gradients (parallel to perpendicular) is less than 10, by, e.g., arrangement of thermal shields outside of the growth chamber.

A method of forming an SiC crystal, the method including: placing a SiC seed in a growth vessel, heating the growth vessel, and evacuating the growth vessel, wherein the seed is levitated as a result of a temperature and pressure gradient, and gas flows from a growth face of the seed, around the edge of the seed, and into a volume behind the seed, which is pumped by a vacuum system.

An SiC single crystal ingot including a silicon carbide (SiC) single crystal formed on a seed crystal, a crystal growth end of a front end of the ingot having a convex shape. An SiC single crystal substrate cut out from a part of a relative height in a height direction of the ingot of at least 0.2 to 0.8 in range has a basal plane dislocation density and threading screw dislocation density observed at the surface of the substrate that are respectively predetermined values or less. Further, the Raman index of the difference (A/B) of the Raman Shift value (A) measured at the center part of the substrate and the Raman Shift value (B) measured at the peripheral parts is a predetermined value or less.

Embodiments of the present disclosure generally relate to apparatus, systems, and methods for in-situ film growth rate monitoring. A thickness of a film on a substrate is monitored during a substrate processing operation that deposits the film on the substrate. The thickness is monitored while the substrate processing operation is conducted. The monitoring includes directing light in a direction toward a crystalline coupon. The direction is perpendicular to a heating direction. In one implementation, a reflectometer system to monitor film growth during substrate processing operations includes a first block that includes a first inner surface. The reflectometer system includes a light emitter disposed in the first block and oriented toward the first inner surface, and a light receiver disposed in the first block and oriented toward the first inner surface. The reflectometer system includes a second block opposing the first block.

The present invention provides a p-type 4HSiC single crystal, which is doped with both aluminum and nitrogen, and has a nitrogen concentration of 2.010.sup.19/cm.sup.3 or more.

Provided herein is a laser processing system integrated with an MBE device, including an MBE growth chamber, a sample table, an optical path mechanism, a heat insulation mechanism, and a cooling mechanism. An opening is formed in a side of the MBE growth chamber. The sample table is fixed in the MBE growth chamber, corresponds to a position of the opening, and is used for placing a substrate sample material. The optical path mechanism is relatively arranged on a side of the MBE growth chamber, and the optical path mechanism is provided with a light-emitting end. A side of the light-emitting end penetrates through the opening of the MBE growth chamber, extends into the MBE growth chamber, and is spaced apart from the sample table. The optical path mechanism is sealedly connected to the opening of the MBE growth chamber. By integrating the optical path mechanism within the MBE device and utilizing direct laser writing, the system facilitates close-range processing of the sample, enhancing the laser's focusing capability and effectively ensuring the precision and quality of laser processing.

The present disclosure provides a method for forming an aluminum nitride single crystalline substrate that includes growing an AlN single crystalline boule followed by cooling the AlN single crystalline boule in three phases including a first cooling phase from the crystal growth temperature to a first intermediate temperature of about 1900? C. to about 1800? C., a second cooling phase from the first intermediate temperature to a second intermediate temperature of about 1500? C. to about 1400? C., wherein the second cooling phase is characterized by a cooling rate of 5.0? C. per minute or less, and a third cooling phase from the second intermediate temperature to room temperature. Also provided is an aluminum nitride single crystalline substrate having a dimensionless figure of merit (FOM) of 0.4 or above and optoelectronic devices made therefrom.

A silicon carbide single crystal includes a region in which a change of a specific resistance is repeated in a growth direction of the silicon carbide single crystal, and the change of the specific resistance is a gradual increase and decrease of the specific resistance. A changing range of the specific resistance may be within a range from 0.5% to 50% inclusive. A changing period of the gradual increase and decrease of the specific resistance that is repeated may be 500 ?m or less in terms of a length of the silicon carbide single crystal.