Abstract: A method of manufacturing a semipolar semiconductor crystal comprising a group-III-nitride (III-N), the method comprising: providing a substrate comprising sapphire (Al2O3) having a first surface that intersects c-planes of the sapphire; forming a plurality of trenches in the first surface, each trench having a wall whose surface is substantially parallel to a c-plane of the substrate; epitaxially growing a group-III-nitride (III-N) material in the trenches on the c-plane surfaces of their walls until the material overgrows the trenches to form a second planar surface, substantially parallel to a (20-2l) crystallographic plane of the group-III-nitride, wherein l is an integer.

Abstract: An epitaxial growth process for producing a thick III-N layer, wherein III denotes at least one element of group III of the periodic table of elements, is disclosed, wherein a thick III-N layer is deposited above a foreign substrate. The epitaxial growth process preferably is carried out by HVPE. The substrate can also be a template comprising the foreign substrate and at least one thin III-N intermediate layer. The surface quality is improved by providing a slight intentional misorientation of the substrate, and/or a reduction of the N/III ratio and/or the reactor pressure towards the end of the epitaxial growth process. Substrates and semiconductor devices with such improved III-N layers are also disclosed.

Abstract: Method for producing a III-N (AlN, GaN, AlxGa(1-x)N) crystal by Vapor Phase Epitaxy (VPE), the method comprising: providing a reactor having: a growth zone for growing a III-N crystal; a substrate holder located in the growth zone that supports at least one substrate on which to grow the III-N crystal; a gas supply system that delivers growth material for growing the III-N crystal to the growth zone from an outlet of the gas supply system; and a heating element that controls temperature in the reactor; determining three growth sub-zones in the growth zone for which a crystal grown in the growth sub-zones has respectively a concave, flat or convex curvature; growing the III-N crystal on a substrate in a growth region for which the crystal has a by desired curvature.

Abstract: In a process for forming a mask material on a III-N layer, wherein III denotes an element of the group III of the Periodic Table of Elements, selected from Al, Ga and In, a III-N layer having a surface is provided which comprises more than one facet. Mask material is selectively deposited only on one or multiple, but not on all facets. The deposition of mask material may be particularly carried out during epitaxial growth of a III-N layer under growth conditions, by which (i) growth of at least a further III-N layer selectively on a first type or a first group of facet(s) and (ii) a deposition of mask material selectively on a second type or a second group of facet(s) proceed simultaneously. By the process according to the invention, it is possible to produce free-standing thick III-N layers. Further, semiconductor devices or components having special structures and layers can be produced.

Abstract: A method and apparatus for growing low defect, optically transparent, colorless, crack-free, substantially flat, single crystal Group III nitride epitaxial layers with a thickness of at least 10 microns is provided. These layers can be grown on large area substrates comprised of Si, SiC, sapphire, GaN, AlN, GaAs, AlGaN and others. In one aspect, the crack-free Group III nitride layers are grown using a modified HVPE technique. If desired, the shape and the stress of Group III nitride layers can be controlled, thus allowing concave, convex and flat layers to be controllably grown. After the growth of the Group III nitride layer is complete, the substrate can be removed and the freestanding Group III nitride layer used as a seed for the growth of a boule of Group III nitride material. The boule can be sliced into individual wafers for use in the fabrication of a variety of semiconductor structures (e.g., HEMTs, LEDs, etc.).

Abstract: HVPE method for simultaneously fabricating multiple Group III nitride semiconductor structures during a single reactor run. A HVPE reactor includes a reactor tube, a growth zone, a heating element and a plurality of gas blocks. A substrate holder is capable of holding multiple substrates and can be a single or multi-level substrate holder. The gas delivery blocks are independently controllable. Gas flows from the delivery blocks are mixed to provide a substantially uniform gas environment within the growth zone. The substrate holder can be controlled, e.g., rotated and/or tilted, for uniform material growth. Multiple Group III nitride semiconductor structures can be grown on each substrate during a single fabrication run of the HVPE reactor. Growth on different substrates is substantially uniform and can be performed on larger area substrates, such as 3-12? substrates.

Abstract: A process for preparing smoothened III-N, in particular smoothened III-N substrate or III-N template, wherein III denotes at least one element of group III of the Periodic System, selected from Al, Ga and In, utilizes a smoothening agent comprising cubic boron nitride abrasive particles. The process provides large-sized III-N substrates or III-N templates having diameters of at least 40 mm, at a homogeneity of very low surface roughness over the whole substrate or wafer surface. In a mapping of the wafer surface with a white light interferometer, the standard deviation of the rms-values is 5% or lower, with a very good crystal quality at the surface or in surface-near regions, measurable, e.g., by means of rocking curve mappings and/or micro-Raman mappings.

Abstract: A method for growing bulk GaN and AlGaN single crystal boules, preferably using a modified HVPE process, is provided. The single crystal boules typically have a volume in excess of 4 cubic centimeters with a minimum dimension of approximately 1 centimeter. If desired, the bulk material can be doped during growth to achieve n-, i-, or p-type conductivity. In order to have growth cycles of sufficient duration, preferably an extended Ga source is used in which a portion of the Ga source is maintained at a relatively high temperature while most of the Ga source is maintained at a temperature close to, and just above, the melting temperature of Ga. To grow large boules of AlGaN, preferably multiple Al sources are used, the Al sources being sequentially activated to avoid Al source depletion and excessive degradation.

Abstract: A method for growing bulk GaN and AlGaN single crystal boules, preferably using a modified HVPE process, is provided. The single crystal boules typically have a volume in excess of 4 cubic centimeters with a minimum dimension of approximately 1 centimeter. If desired, the bulk material can be doped during growth to achieve n-, i-, or p-type conductivity. In order to have growth cycles of sufficient duration, preferably an extended Ga source is used in which a portion of the Ga source is maintained at a relatively high temperature while most of the Ga source is maintained at a temperature close to, and just above, the melting temperature of Ga. To grow large boules of AlGaN, preferably multiple Al sources are used, the Al sources being sequentially activated to avoid Al source depletion and excessive degradation.

Abstract: The present invention relates to a novel process for producing (Al, Ga)N and AlGaN single crystals by means of a modified HVPE process, and also to (Al, Ga)N and AlGaN single crystals of high quality. The III-V compound semiconductors produced by the process according to the invention are used in optoelectronics, in particular for blue, white and green LEDs and also for high-power, high-temperature and high-frequency field effect transistors.

Abstract: The present invention relates to a novel process for producing (Al, Ga)InN and AlGaInN single crystals by means of a modified HVPE process, and also to (Al, Ga)InN and AlGaInN bulk crystals of high quality, in particular homogeneity. The III-V compound semiconductors produced by the process according to the invention are used in optoelectronics, in particular for blue, white and green LEDs and also for high-power, high-temperature and high-frequency field effect transistors.

Abstract: In a process for manufacturing doped semiconductor single crystal comprises solidifying in a crucible, the amount of dopant is added into the semiconductor melt after the beginning of the crystal growth onto the seed crystal, or after at least partial solidification of the semiconductor single crystal in a conical or tapered portion of the crucible. Dopant may be partially added in advance into the crucible, with the remainder added into the semiconductor melt as described. Type III-V semiconductor single crystals or wafers having a diameter of at least about 100 mm, can be prepared having an electrical conductivity of at least about 250 Siemens/cm, and/or an electric resistivity of at most about 4×10?3 ?cm, and/or a significantly improved ratio of hall mobility to charge carrier concentration.

Abstract: The invention relates to a method for producing c-plane GaN substrates or AlxGa1-xN substrates using an original substrate. Said method is characterized by the following steps: a tetragonal (100)-oriented or (?100)-oriented original LiAlO2 substrate is used; said original substrate is nitrided in a nitrogen compound-containing atmosphere at temperatures lying below the decomposition temperature of LiAlO2; a nucleation layer is grown at temperatures ranging between 500° C. and 700° C. by adding GaCl or AlCl or a mixture of GaCl and AlCl in a nitrogen compound-containing atmosphere; single-crystalline c-plane-oriented GaN or AlxGa1-xN is grown on the nucleation layer at temperatures ranging between 900° C. and 1050° C. by means of hydride vapor phase epitaxy (HVPE) with GaCl or AlCl or a GaCl/AlCl mixture in a nitrogen compound-containing atmosphere; and the substrate is cooled.

Abstract: An epitaxial growth process for producing a thick III-N layer, wherein III denotes at least one element of group III of the periodic table of elements, is disclosed, wherein a thick III-N layer is deposited above a foreign substrate. The epitaxial growth process preferably is carried out by HVPE. The substrate can also be a template comprising the foreign substrate and at least one thin III-N intermediate layer. The surface quality is improved by providing a slight intentional misorientation of the substrate, and/or a reduction of the N/III ratio and/or the reactor pressure towards the end of the epitaxial growth process. Substrates and semiconductor devices with such improved III-N layers are also disclosed.

Abstract: A wire saw (1; 100) for cutting a workpiece includes a device (21, 22, 24, 27) for setting, controlling and/or maintaining a predetermined or desired water content in at least part of the gaseous medium that contacts the slurry. With the wire saw according to the invention and the process carried out using this wire saw, it is possible to achieve consistently good surface properties of the resulting wafers over a prolonged period of use of a slurry.

Abstract: A method for the division of single crystals, in particular of GaAs, is provided in which a single crystal (1) to be cut into at least two parts and a cutting tool (2, 3; 8, 8a, 8b, 8c) are moved relative to one another in a direction of advancement (V) and wherein the single crystal (1) is oriented in such a way that a specified crystallographic orientation (K) lies in the cutting plane (T), characterized in that an angle (?) between the specified crystallographic direction (K) and the direction of advancement (V) is chosen in such a way that forces which act on the cutting tool during cutting in a direction at right angles to the cutting plane compensate one another.

Abstract: An apparatus and a method for determining the orientation of a crystallographic plane (100) relative to a crystal surface (2) are provided, in which the orientation is free from errors of adhesion of the crystal or contamination of the holders for the crystal. For this purpose, the angle which the crystal surface to be measured forms with a reference axis and the angle which the crystallographic plane forms with the reference axis are measured and subtracted. In a wire sawing apparatus with an X-Y positioning unit, next the desired correction is made with the aid of measurement of the orientation and at the same time the crystal is displaced in horizontal and vertical positions. As a result, there remains a further degree of freedom of rotation of the crystal in the cutting plane for achieving a cut which is free from forces perpendicular to the feed direction and wire direction, so that no tool deflection takes place or the cutting forces are minimal. Further, the precision of orientation is increased.

Abstract: In a method and an apparatus for producing monocrystals, in particular of gallium arsenide monocrystals, the crystal growth is carried out with a thermal shock resistant nucleus which is freely standing within a nucleus channel and the interspace in the nucleus channel between the nucleus and the crucible is filled with liquid boric oxide.

Abstract: There is provided a heating element and an arrangement of heating elements, respectively, for heating crucibles, in particular for LEC devices for growing semiconductor single crystals, with a tulip-shaped bottom heater (20) being built such that the heater legs of the main heater (40) positioned thereabove can barely be guided towards the bottom. Such arrangement of bottom and main heater enables multi-heater arrangements without having to interfere with a lateral insulation (18) which, thus, need not be cut out or pierced.