Abstract: The present invention relates to a seed crystal assembly for growing a single crystal boule in a physical vapor transport, PVT, process. Furthermore, the invention relates to a method for producing a bulk SiC crystal in a physical vapor transport growth system. A seed crystal assembly comprises a base structure which is connectable to a crucible, the base structure having a base diameter across a central axis of the seed crystal assembly and base height along the central axis, and a single crystal seed crystal which is designed for growing the single crystal boule on a growth surface. The single crystal seed crystal is attached to the base structure, the seed crystal having a seed crystal diameter across the central axis and a seed crystal height along the central axis, wherein a specific heat conductivity of the base structure differs by less than or equal to 25% from a specific heat conductivity of the seed crystal at a growth temperature between 2000° C. and 2600° C.

Abstract: A floor structure, and a relative method for controlling the temperature, comprising a floor layer, a supporting layer realizing a continuous air chamber having an aerial extension comparable to an aerial extension of a floor surface, and an air movement system to generate an air flow through the floor layer from the air chamber to the floor surface and/or viceversa, the air movement system comprising one or more air mouths opening into the air chamber at a distance from a side surface of the air chamber.

Abstract: A method for aligning two surveying instruments in a common space in a process that uses an autocollimation of a collimated light beam transmitted by a first surveying instrument and reflected by a second surveying instrument. In the alignment process, the first surveying instrument may emit a collimated light beam towards the second the surveying instrument and receive a reflection of the collimated light beam from the second surveying instrument in an autocollimator. The reflection may be generated for example by a mirror at the second surveying instrument. When the light beam is reflected such that autocollimation of the collimated light beam is achieved at the first surveying instrument, the first and second surveying instruments are in a predetermined positional relation with respect to one another.

Abstract: The present invention provides a monocrystalline SiC substrate with an asymmetric shape for enhancing substrate stiffness against thermal induced deformations, the substrate comprising: a main region, and an asymmetric region located at a peripheral region of the substrate and adjacent to the main region, wherein the asymmetric region is inclined inwards, relative to the main region, to provide an asymmetric shape to the substrate. The present invention also provides a method of producing one or more substrates with an asymmetric shape, comprising: performing a multi-wire sawing process in which one or more substrates are cut with an wire-sawing web from an ingot placed on a stage, and cutting the one or more substrates with the asymmetric shape by controlling a relative movement between the wire-sawing web and the stage, the relative movement causing the wire-sawing web to describe a non-linear sawing path across the ingot to cut the asymmetric shape.

Abstract: The present invention relates to a chamfered silicon carbide substrate which is essentially monocrystalline, and to a corresponding method of chamfering a silicon carbide substrate. A silicon carbide substrate according to the invention comprises a main surface (102), wherein an orientation of said main surface (102) is such that a normal vector ({right arrow over (O)}) of the main surface (102) includes a tilt angle with a normal vector ({right arrow over (N)}) of a basal lattice plane (106) of the substrate, and a chamfered peripheral region (110), wherein a surface of the chamfered peripheral region includes a bevel angle with said main surface, wherein said bevel angle is chosen so that, in more than 75% of the peripheral region, normal vectors ({right arrow over (F)}_i) of the chamfered peripheral region (110) differ from the normal vector of the basal lattice plane by less than a difference between the normal vector of the main surface and the normal vector of the basal lattice plane of the substrate.

Abstract: A surveying system comprises a base 3, a first alidade 7 mounted on the base and rotatable relative to the base about a first axis 9, a first optical instrument 17 mounted on the first alidade 7, wherein the first optical instrument is configured to emit a first beam 41 of measuring light, a second alidade 19 mounted on the base and rotatable relative to the base about a second axis 21, and a second optical instrument 25 mounted on the second alidade, wherein the second axis substantially coincides with the first axis. The first optical instrument includes a scanner 31, and the second optical instrument includes at least one camera 63.

Abstract: The present invention relates to a silicon carbide (SiC) substrate with improved mechanical and electrical characteristics. Furthermore, the invention relates to a method for producing a bulk SiC crystal in a physical vapor transport growth system. The silicon carbide substrate comprises an inner region (102) which constitutes at least 30% of a total surface area of said substrate (100), a ring shaped peripheral region (104) radially surrounding the inner region (102), wherein a mean concentration of a dopant in the inner region (102) differs by at least 1·1018 cm?3 from the mean concentration of this dopant in the peripheral region (104).

Abstract: The present disclosure relates to a layered seed for growing a volume mono crystal by gas phase growth in a direction of growth (Y) in a crucible. The layered seed comprises a monocrystalline growing layer with a growing surface for growing the volume mono crystal and an opposing heat spreader facing surface for coupling the growing layer to a heat spreader layer. The layered seed further comprises the heat spreader layer with a growing layer facing surface for coupling to the heat spreader facing surface and an opposing mounting surface for mounting the heat spreader layer to the crucible, wherein the heat spreader layer comprises a polycrystalline material having thermally coupled grains that are piled in the direction of growth (Y), the piled grains for equalizing hot spots of the crucible thermally coupled to the mounting surface.

Abstract: The present invention provides a multilayer seed which is designed such as to offer a virtually unstressed surface onto which a single-crystal can grow without the negative impact of the internal stress carried by monocrystalline seeds, in particular at the high temperatures conventionally used in sublimation processes. The multilayer seed for growing a single-crystal comprise at least two seed layers, wherein each of the at least two seed layers is a monocrystalline layer characterized by one or more parameters associated with a respective degree of internal stress. The one or more parameters are selected such that the at least two seed layers are adapted to counter-act the respective internal stresses from each other.

Abstract: The present disclosure relates to a layered substrate for growing an epitaxial layer in a direction of growth (Y) in a reactor. The layered substrate comprises a monocrystalline growing layer with a growing surface for growing the epitaxial layer and an opposing heat spreader facing surface for coupling the growing layer to a heat spreader substrate. The layered substrate further comprises the heat spreader substrate with a growing layer facing surface for coupling to the heat spreader facing surface and an opposing mounting surface for mounting the heat spreader substrate to the reactor, wherein the heat spreader substrate comprises a polycrystalline material having thermally coupled grains that are piled in the direction of growth (Y), the piled grains for equalizing hot spots of the reactor thermally coupled to the mounting surface.

Abstract: A bulk SiC single crystal is produced by sublimation growth. A stress measurement to detect initial internal mechanical seed stresses is carried out on a wafer-shaped single crystalline SiC seed crystal. The seed crystal is classified, according to the stress measurement, into a first class when the initial seed stresses are below a first stress boundary value, into a second class when the initial seed stresses lie between the first stress boundary value and a second stress boundary value, and into a third class when the initial seed stresses exceed the second stress boundary value. The actual sublimation growth for growing the bulk SiC single crystal is carried out with the SiC seed crystal only when it has been classified into the first or second class, and when it is classified into the second class, at least one stress-reducing measure is carried out.

Abstract: A seed unit for growing a bulk SiC single crystal has a wafer-like single crystalline SiC seed crystal with a growth surface arranged on a wafer front side for growing the bulk SiC single crystal to be grown. The SiC seed crystal has a crystal longitudinal mid-axis extending in an axial direction. A radial direction is oriented perpendicular to the axial direction. The seed unit also has a rear side layer component arranged on a wafer rear side of the SiC seed crystal, the structure of which changes starting from the crystal longitudinal mid-axis in the radial direction, and so a radial temperature gradient is adjusted during the growth of the bulk SiC single crystal within the SiC seed crystal.

Abstract: The present invention relates to an implant for determining a pressure difference inside a bodily lumen, comprising: an implantable body, the implantable body comprising a first conductive element and a second conductive element, the first and second conductive elements being electrically insulated relative to each other, first and second pressure sensors, the first and second pressure sensors being arranged for measuring a pressure occurring inside the body, the first and second pressure sensors being arranged at different locations, wherein the first pressure sensor is arranged for sending the pressure to a remote read-out device by means of being coupled to the first conductive element, with the first conductive element serving as an antenna, and wherein the second pressure sensor is arranged for sending the pressure to a remote read-out device by means of being coupled to the second conductive element, with the second conductive element serving as an antenna.

Abstract: The present invention relates to a crucible with a cavity for growing a SiC volume mono crystal by sublimation growth in a direction of growth (Y). The crucible comprises an end wall (110) with a seed holder (112) for holding a SiC seed crystal in the cavity, the end wall (110) extending in a direction (r) perpendicular to the direction of growth (Y); a side wall (140) extending in the direction of growth (Y), the side wall (140) preventing permeation of a doping gas from an external into the cavity, the doping gas for doping the SiC volume mono crystal during the sublimation growth; and a diffusion region (114) allowing permeation of the doping gas from the external in the cavity, wherein the diffusion region (114) is located between the seed holder (112) and an edge (142) of the side wall (140).

Abstract: An arrangement for growing a SiC volume monocrystal in a cavity (110) by sublimation growth in the direction of growth (Y) includes a susceptor (100) for absorbing electromagnetic energy and heating the cavity (110). An insulator (200) surrounds the susceptor (100) to thermally insulate it from the exterior. The insulator (200) features a thermal insulation wall (202) that reduces radial heat transfer (r) from the susceptor (100). A thermally conductive layer (210) is positioned between the susceptor (100) and the thermal insulation wall (202) to distribute heat and minimize or reduce thermal conduction to the insulator (200), enhancing the insulator's reflectivity and reducing waviness.

Abstract: The present invention provides monocrystalline 4H—SiC semi-finished products having a specific orientation of its crystal structure which is set such as to reduce or even eliminate the occurrence of cracks or fissures during mechanical processing, and method of producing same. The monocrystalline 4H—SiC semi-finished product, which has a longitudinal axis and an at least partially curved lateral surface parallel to said longitudinal axis, is characterized in that the crystal structure of the 4H—SiC semi-finished product is oriented with respect to the longitudinal axis such that at each position on the lateral surface of the semi-finished product there is a line segment which is intersected by at least a predetermined minimum number of parallel cleavage planes of the {1010} form per unit length, wherein the line segment is defined by a plane tangent to the lateral surface at said position.

Abstract: An optical surveying instrument is provided with an optical arrangement that includes at least one lens and the viewing element defining a viewing direction in the field of view. The distance measurement unit emits light beam towards the field of view and measured the distance to an object in the field of view based on a reflection of the light beam from the object. A movable mirror is arranged to direct the light beam towards the object and a mirror control unit is provided for reading calibration values from a calibration value memory and for moving the movable mirror using the calibration values to adjust the direction of the light beam to be aligned with the viewing direction.

Abstract: A method for simultaneously manufacturing more than one single crystal of a semiconductor material by physical vapor transport (PVT) includes connecting a pair of reactors to a vacuum pump system by a common vacuum channel and creating and/or controlling, with the vacuum pump system, a common gas phase condition in the inner chambers of the pair of reactors. Each reactor has an inner chamber adapted to accommodate a PVT growth structure for growth of a semiconductor single crystal.

Abstract: A scanning surveying system comprises a base 5, an alidade 3 mounted on the base, a first motor 6 to rotate the alidade about a first axis 9, a rotating mirror 21 rotatable about a second axis 16, a second motor 23 to rotate the mirror. An optical distance measuring unit 11 is configured to direct measuring light onto the rotating mirror such that it is reflected towards objects and to receive measuring light back from these objects via the rotating mirror. The system further comprises a camera 81 and a controller for controlling the first motor based on the images recorded by the camera such that the measuring light is reflected from the rotating mirror in a direction corresponding to a selected location within the image.

Abstract: Thermal post-treatment of a silicon carbide (SiC) volume monocrystal which has a substantially cylindrical basic shape with a crystal length in an axial direction, a crystal diameter in a radial direction, a crystal central longitudinal axis extending in the axial direction, and with three boundary surfaces, namely, a bottom surface, a top surface and a circumferential edge surface. The SiC volume monocrystal is brought to a post-treatment temperature in order to reduce mechanical stresses present in the SiC volume monocrystal after completion of the previous growth, wherein an inhomogeneous temperature profile with a radial thermal gradient is set in the SiC volume monocrystal, which rises continuously from the crystal central longitudinal axis to the circumferential edge surface, and a heat exchange of the SiC volume monocrystal with a surrounding free space takes place via free heat radiation on at least two of the three boundary surfaces.