87results about How to "Reduce threading dislocation density" patented technology

A surface of a sapphire (0001) substrate is processed to form recesses and protrusions so that protrusion tops are flat and a given plane-view pattern is provided. An initial-stage AlN layer is grown on the surface of the sapphire (0001) substrate having recesses and protrusions by performing a C+ orientation control so that a C+ oriented AlN layer is grown on flat surfaces of the protrusion tops, excluding edges, in such a thickness that the recesses are not completely filled and the openings of the recesses are not closed. An Al_xGa_yN(0001) layer (1≧x>0, x+y=1) is epitaxially grown on the initial-stage AlN layer by a lateral overgrowth method. The recesses are covered with the Al_xGa_yN(0001) layer laterally overgrown from above the protrusion tops. Thus, an template for epitaxial growth having a fine and flat surface and a reduced threading dislocation density is produced.

A method for minimizing particle generation during deposition of a graded Si_1-xGe_x layer on a semiconductor material includes providing a substrate in an atmosphere including a Si precursor and a Ge precursor, wherein the Ge precursor has a decomposition temperature greater than germane, and depositing the graded Si_1-xGe_x layer having a final Ge content of greater than about 0.15 and a particle density of less than about 0.3 particles/cm² on the substrate.

The present invention relates to a method of forming a nitride semiconductor substrate. This method includes steps of providing a substrate and then forming an epitaxy layer on the substrate. A patterned mask layer is formed on the epitaxy layer, wherein the patterned mask layer exposes a portion of the epitaxy layer. Next, an oxidation process is performed to oxidize the exposed epitaxy layer so as to form a plurality of dislocation blocking structures. The patterned mask layer is then removed. Further, a nitride semiconductor layer is formed on the epitaxy layer having the dislocation blocking structures.

A semiconductor substrate (1) of the present invention is made of nitrides of group III metals having wurtzite crystal structure and is grown in vapor phase either on a (0001) oriented foreign substrate (2), lattice mismatched to the semiconductor substrate materials, or on existing (0001) oriented highly dislocated layer (3) of the semiconductor substrate materials and has a highly reduced dislocation density. According to the present invention, a structure is utilized for the dislocation density reduction, which comprises a dislocation redirection layer (4) providing intentional inclination of threading dislocations (6) towards high index crystallographic planes having crystallographic indexes other than (0001) and those of the type {1 100}, in order to enhance the probability for dislocation reactions; and a dislocation reaction layer (5) positioned above said dislocation layer (4), in which the threading dislocations (6) coalesce with each other resulting in reduced threading dislocation density at the semiconductor substrate surface (7).

The invention discloses a device and a method for preparing a high-quality large-diameter SiC single crystal, which belong to the field of SiC crystal growth, the device comprises a crucible, a thermal insulation layer, a heating device and a porous graphite barrel; wherein the crucible is positioned in the thermal insulation layer; the heating device is located on the outer side of the thermal insulation layer; the seed crystal and a porous graphite barrel are positioned in the crucible and are coaxial with the crucible; according to the invention, a transportation mode of the SiC growth components is from raw materials on the outer side of the crucible to seed crystals on the inner side of the crucible, the crystal growth process is a natural expanding process, expanding of the diameterof the crystal is not limited, meanwhile, the crystal grows along a non-polar growth face, and the penetration dislocation density is greatly reduced compared with that of the crystal growing along aC axis; C particles generated by the SiC raw material which is heated and carbonized next to the crucible wall are effectively blocked by the SiC raw material on the inner side and the porous graphitelayer, so that C inclusions in the crystal are reduced, and the quality of the crystal is effectively improved.