Aspects of the present disclosure are directed to circuitry operable with enhanced capacitance and mitigation of avalanche breakdown. As may be implemented in accordance with one or more embodiments, an apparatus and/or method involves respective transistors of a cascode circuit, one of which controls the other in an off state by applying a voltage to a gate thereof. A plurality of doped regions are separated by trenches, with the conductive trenches being configured and arranged with the doped regions to provide capacitance across the source and the drain of the second transistor, and restricting voltage at one of the source and the drain of the second transistor, therein mitigating avalanche breakdown of the second transistor.

A semiconductor device having a voltage resistant structure in a first aspect of the present invention is provided, comprising a semiconductor substrate, a semiconductor layer on the semiconductor substrate, a front surface electrode above the semiconductor layer, a rear surface electrode below the semiconductor substrate, an extension section provided to a side surface of the semiconductor substrate, and a resistance section electrically connected to the front surface electrode and the rear surface electrode. The extension section may have a lower permittivity than the semiconductor substrate. The resistance section may be provided to at least one of the upper surface and the side surface of the extension section.

Multiple wide bandgap semiconductor wafers, each having active circuitry and an epitaxially formed backside drain contact layer, may be constructed from a single bulk semiconductor substrate by: forming foundational layers on the top of the bulk substrate via epitaxy; forming active circuitry atop the foundational layers; laser treating the backside of the bulk substrate to create a cleave line in one of the foundational layers; and exfoliating a semiconductor wafer from the bulk substrate, where the exfoliated semiconductor wafer contains the active circuits and at least a portion of the foundational layers. Wafers containing the foundational layers without complete active devices may be produced in a similar manner. The foundational layers may comprise a drain contact layer and a drift layer, and may additionally include a buffer layer between the drain contact layer and the drift layer.

A semiconductor device of the present invention includes a semiconductor layer, a gate trench that defines a source region of a first conductivity type in the semiconductor layer, a channel region of a second conductivity type of a lower part of the source region, a source trench that passes through the source region and the channel region, an impurity region of the second conductivity type of a bottom part and a side part of the source trench, a source electrode on the semiconductor layer, and a highly-concentrated impurity region of the second conductivity type, the highly-concentrated impurity region having a contact portion connected to the source electrode at a surface of the semiconductor layer, the highly-concentrated impurity region passing through the source region and extending to a position deeper than the source region, the highly-concentrated impurity region having a concentration higher than the impurity region.

A field effect gas sensor, for detecting a presence of a gaseous substance in a gas mixture, the field effect gas sensor comprising: a SiC semiconductor structure; an electron insulating layer covering a first portion of the SiC semiconductor structure; a first contact structure at least partly separated from the SiC semiconductor structure by the electron insulating layer; and a second contact structure conductively connected to a second portion of the SiC semiconductor structure, wherein at least one of the electron insulating layer and the first contact structure is configured to interact with the gaseous substance to change an electrical property of the SiC semiconductor structure; and wherein the second contact structure comprises: an ohmic contact layer in direct contact with the second portion of the SiC semiconductor structure; and a barrier layer formed by an electrically conducting mid-transition-metal oxide covering the ohmic contact layer.

A method for preparing a SiC ingot includes: preparing a reactor by disposing a raw material in a crucible body and disposing a SiC seed in a crucible cover, and then wrapping the crucible body with a heat insulating material having a density of 0.14 to 0.28 g/cc; and growing the SiC ingot from the SiC seed by placing the reactor in a reaction chamber and adjusting an inside of the reactor to a crystal growth atmosphere such that the raw material is vapor-transported and deposited to the SiC seed.

A silicon carbide semiconductor device has a silicon carbide substrate and an insulating film. The silicon carbide substrate includes a termination region having a peripheral edge, and an element region surrounded by the termination region. The insulating film is provided on the termination region. The termination region includes a first impurity region having a first conductivity type, and a field stop region having the first conductivity type, being in contact with the first impurity region and having a higher impurity concentration than the first impurity region. The field stop region is at least partially exposed at the peripheral edge.

A semiconductor structure includes a substrate, first fins extending from the substrate with a first fin pitch, and second fins extending from the substrate with a second fin pitch smaller than the first fin pitch. The semiconductor structure also includes first gate structures engaging the first fins with a first gate pitch and second gate structures engaging the second fins with a second gate pitch smaller than the first gate pitch. The semiconductor structure also includes first epitaxial semiconductor features partially embedded in the first fins and adjacent the first gate structures and second epitaxial semiconductor features partially embedded in the second fins and adjacent the second gate structures. A bottom surface of the first epitaxial semiconductor features is lower than a bottom surface of the second epitaxial semiconductor features.

A method for manufacturing an epitaxial wafer comprising a silicon carbide substrate and a silicon carbide voltage-blocking-layer, the method includes: epitaxially growing a buffer layer on the substrate, doping a main dopant for determining a conductivity type of the buffer layer and doping an auxiliary dopant for capturing minority carriers in the buffer layer at a doping concentration less than the doping concentration of the main dopant, so that the buffer layer enhances capturing and extinction of the minority carriers, the minority carriers flowing in a direction from the voltage-blocking-layer to the substrate, so that the buffer layer has a lower resistivity than the voltage-blocking-layer, and so that the buffer layer includes silicon carbide as a main component; and epitaxially growing the voltage-blocking-layer on the buffer layer.

A semiconductor device includes an anode doping region of a diode structure arranged in a semiconductor substrate. The anode doping region has a first conductivity type. The semiconductor device further includes a second conductivity type contact doping region having a second conductivity type. The second conductivity type contact doping region is arranged at a surface of the semiconductor substrate and surrounded in the semiconductor substrate by the anode doping region. The anode doping region includes a buried non-depletable portion. At least part of the buried non-depletable portion is located below the second conductivity type contact doping region in the semiconductor substrate.