Abstract: Semiconductor structures including parallel graphene nanoribbons or carbon nanotubes oriented along crystallographic directions are provided from a template of silicon carbide (SiC) fins or nanowires. The SiC fins or nanowires are first provided and then graphene nanoribbons or carbon nanotubes are formed on the exposed surfaces of the fin or the nanowires by annealing. In embodiments in which closed carbon nanotubes are formed, the nanowires are suspended prior to annealing. The location, orientation and chirality of the graphene nanoribbons and the carbon nanotubes that are provided are determined by the corresponding silicon carbide fins and nanowires from which they are formed.

Abstract: A semiconductor device includes a substrate, a first doped well disposed in the substrate, a second doped well disposed in the substrate adjacent to a first side of the first doped well, a buffer region disposed in the first doped well adjacent to a second and opposite side of the first doped well, a gate structure disposed above the first side of the first doped well and extending along a first horizontal direction, a first contact region disposed in the buffer region toward the second side of the first doped well, a second contact region disposed in the buffer region adjacent to the first contact region, and a doped region disposed in the buffer region under the first contact region.

Abstract: A semiconductor device includes an n-type semiconductor substrate, which has a main surface having an element region and an outer peripheral region surrounding the element region; a p-type guard ring, which includes: a lowly-doped p-type region disposed on an upper surface of the semiconductor substrate in the outer peripheral region surrounding the element region; and a highly-doped p-type region disposed on an inner side of the lowly-doped p-type region and having an impurity concentration higher than an impurity concentration of the lowly-doped p-type region, wherein a side surface and a bottom surface of the highly-doped p-type region are covered by the lowly-doped p-type region such that the highly-doped p-type region is not in contact with the n-type region; and an ohmic junction electrode, which forms an ohmic junction with the highly-doped p-type region.

Abstract: A semiconductor device includes: a p-type semiconductor layer; an n-type semiconductor layer; a first electrode layer; a second electrode layer; and a control electrode layer. The first and second electrode layers are electrically connected such as to each operate at an identical potential. The first electrode layer is connected with a part of a surface of the second electrode layer which is opposite to a surface of the second electrode layer that is in contact with the p-type semiconductor layer. The second electrode layer is connected with a connection line which is a part of a peripheral line of a joint interface between the p-type semiconductor layer and the n-type semiconductor layer on an interface side between the second electrode layer and the p-type semiconductor layer, and is formed to be extended to a position on a control electrode layer side of the connection line.

Abstract: A mechanism relates to a superconducting quantum system. A diamond substrate layer is included. A superconducting quantum device is disposed on the diamond substrate layer. The superconducting quantum device includes a superconducting quantum circuit formed on top a surface of the diamond substrate layer.

Abstract: A wide bandgap semiconductor device includes a wide bandgap semiconductor layer and a Schottky electrode. The wide bandgap semiconductor layer includes a first impurity region which is in contact with the Schottky electrode, is in contact with a second main surface, and has a first conductivity type, and a second impurity region which is in contact with the Schottky electrode, is in contact with the first impurity region, and has a second conductivity type. The second impurity region has a first region which is in contact with the Schottky electrode, and a second region which is connected with the first region and provided on a side of the first region closer to the second main surface. A maximum value of a width of the second region is larger than a width of a boundary portion between the first region and the Schottky electrode.

Abstract: According to one embodiment, a semiconductor device includes first electrode, second electrode, and third electrodes, first, second, third, fourth, and fifth semiconductor regions. The first semiconductor region is provided between the first and second electrodes. The second semiconductor region is provided between the first semiconductor region and the second electrode. The third semiconductor region is provided between the second semiconductor region and the second electrode. The third semiconductor region has an impurity concentration higher than an impurity concentration of the first semiconductor region. The third electrode contacts the third, second, and first semiconductor regions via an insulating film. The fourth semiconductor region is provided between the first semiconductor region and the second electrode. The fifth semiconductor region is provided between the fourth semiconductor region and the second electrode.

Abstract: A method for forming a semiconductor device includes forming a dielectric layer on a first substrate and wafer bonding the dielectric layer of the first substrate to a second substrate including SiC with a passivating layer formed on the SiC. A portion of the first substrate is removed from a side opposite the dielectric layer. The dielectric layer is patterned to form a gate dielectric for a field effect transistor formed on the second substrate.

Abstract: An n-type SiC layer is formed on a front face of an n+-type SiC substrate and plural p-type regions are selectively formed inside the n-type SiC layer. A p-type SiC layer is formed covering the surfaces of the n-type SiC layer and the p-type regions. An n-type region is formed inside the p-type SiC layer to be connected to the n-type SiC layer. An n+-type source region and a p+-type contact region are formed inside the p-type SiC layer, positioned away from the n-type region and in contact with each other. The n-type region in the p-type SiC layer is formed such that the width LJFET of the n-type region is within a range from 0.8 ?m to 3.0 ?m and the impurity concentration of the n-type region is greater than 1.0×1016 cm?3 and less than or equal to 5.0×1016 cm?3.

Abstract: The present invention relates to a method for separating semiconductor devices from a substrate using a nanoporous structure, wherein electrochemical etching is carried out in the absence of a surface metal layer, then the surface metal layer is deposited, and then a GaN thin film is transferred onto a metal wafer by means of wafer bonding and lift-off.

Abstract: The invention generally related to a method for preparing a layer of graphene directly on the surface of a semiconductor substrate. The method includes forming a carbon-containing layer on a front surface of a semiconductor substrate and depositing a metal film on the carbon layer. A thermal cycle degrades the carbon-containing layer, which forms graphene directly upon the semiconductor substrate upon cooling. In some embodiments, the carbon source is a carbon-containing gas, and the thermal cycle causes diffusion of carbon atoms into the metal film, which, upon cooling, segregate and precipitate into a layer of graphene directly on the semiconductor substrate.

Abstract: It is an object of the present invention to provide a silicon carbide semiconductor device that reduces an influence of an off-angle of a silicon carbide substrate on characteristics of the semiconductor device and achieves improved operational stability and reduced resistance. In a trench-gate silicon carbide MOSFET semiconductor device formed on the silicon carbide semiconductor substrate having the off-angle, a low-channel doped region is provided on a first sidewall surface side of the trench in a well region, and a high-channel doped region having an effective acceptor concentration lower than that of the low-channel doped region is provided on a second sidewall surface side of the trench in the well region.

Abstract: A semiconductor device includes a first electrode, a second electrode, a first semiconductor layer of a first conductivity type located between the first electrode and the second electrode and having a region in which a carbon vacancy density becomes lower in a first direction from the first electrode to the second electrode, a second semiconductor layer of the first conductivity type located between the first electrode and the first semiconductor layer and having an impurity element concentration higher than the impurity element concentration of the first semiconductor layer, and a plurality of third semiconductor layers of a second conductivity type located between the second electrode and the first semiconductor layer.

Abstract: A method of fabricating a multi-layer epitaxial buffer layer stack for transistors includes depositing a buffer stack on a substrate. A first voided Group IIIA-N layer is deposited on the substrate, and a first essentially void-free Group IIIA-N layer is then deposited on the first voided Group IIIA-N layer. A first high roughness Group IIIA-N layer is deposited on the first essentially void-free Group IIIA-N layer, and a first essentially smooth Group IIIA-N layer is deposited on the first high roughness Group IIIA-N layer. At least one Group IIIA-N surface layer is then deposited on the first essentially smooth Group IIIA-N layer.

Abstract: 4H SIC epiwafers with thickness of 50-100 ?m are grown on 4° off-axis substrates. Surface morphological defect density in the range of 2-6 cm?2 is obtained from inspection of the epiwafers. Consistent carrier lifetime in the range of 2-3 ?s has been obtained on these epiwafers. Very low BPD density has been confirmed in the epiwafers with BPD density down to below 10 cm?2. Epitaxial wafers with thickness of 50-100 ?m have been used to fabricate diodes. High voltage testing has demonstrated blocking voltages near the theoretical values for 4H-SiC. Blocking voltage as high as 8 kV has been achieved in devices fabricated on 50 ?m thick epitaxial films, and blocking voltage as high as 10 kV has been obtained in devices fabricated on 80 ?m thick films. Failure analysis confirmed triangle defects, which form from surface damage or particles present during epitaxy, are killer defects and cause the device to fail in reverse bias operation.

Abstract: A semiconductor-carbon alloy layer is formed on the surface of a semiconductor substrate, which may be a commercially available semiconductor substrate such as a silicon substrate. The semiconductor-carbon alloy layer is converted into at least one graphene layer during a high temperature anneal, during which the semiconductor material on the surface of the semiconductor-carbon alloy layer is evaporated selective to the carbon atoms. As the semiconductor atoms are selectively removed and the carbon concentration on the surface of the semiconductor-carbon alloy layer increases, the remaining carbon atoms in the top layers of the semiconductor-carbon alloy layer coalesce to form a graphene layer having at least one graphene monolayer. Thus, a graphene layer may be provided on a commercially available semiconductor substrate having a diameter of 200 mm or 300 mm.

Abstract: The invention relates to a method for producing a component comprising a conductive grid insulated from a semiconductor monocrystalline diamond substrate by an insulating region, comprising the following steps: a) oxygenating the surface of the substrate so as to replace the hydrogen surface terminations of the substrate with oxygen surface terminations; and b) forming the insulating region on the surface of the substrate by repeated monatomic layer deposition.

Abstract: A silicon carbide semiconductor device includes a junction barrier Schottky diode including a substrate, a drift layer, an insulating film, a Schottky barrier diode, and a plurality of second conductivity type layers. The Schottky barrier diode includes a Schottky electrode and an ohmic electrode. A PN diode is configured by the plurality of second conductivity type layers and the drift layer, and the plurality of second conductivity type layers is formed in stripes only in a direction parallel to a rod-shaped stacking fault.

Abstract: A semiconductor structure includes a first semiconductor region. The first semiconductor region includes a first semiconductor layer composed of a group IV semiconductor material having a top surface and a back surface. The first semiconductor layer has an opening in the top surface to at least a depth greater than an aspect ratio trapping (ART) distance. The first semiconductor region also has a second semiconductor layer composed of a group III/V semiconductor compound deposited within the opening and on the top surface of the first semiconductor layer. The second semiconductor layer forms an ART region from the bottom of the opening to the ART distance.

Abstract: According to one embodiment, a semiconductor device includes a first semiconductor region, a second semiconductor region, a third semiconductor region, an insulating film, and a control electrode. The first semiconductor region includes a silicon carbide of a first conductivity type. The second semiconductor region is provided on the first semiconductor region, includes a silicon carbide of a second conductivity type, and has a first main surface. The third semiconductor region is provided on the second semiconductor region and includes the silicon carbide of the first conductivity type. The film is provided on the surface. The electrode is provided on the film, and has a first region close to the third semiconductor region side, and a second region closer to the first semiconductor region side than the first region. An effective work function of the first region is larger than an effective work function of the second region.

Abstract: A silicon carbide single-crystal substrate includes a first surface, a second surface opposite to the first surface, and a peripheral edge portion sandwiched between the first surface and the second surface. A plurality of grinding traces are formed in a surface of the peripheral edge portion. A chamfer width as a distance from an outermost peripheral end portion of the peripheral edge portion to one of the plurality of grinding traces which is located on an innermost peripheral side of the peripheral edge portion in a direction parallel to the first surface is not less than 50 ?m and not more than 400 ?m. Thereby, a silicon carbide single-crystal substrate capable of suppressing occurrence of a crack, and a method for manufacturing the same can be provided.

Abstract: A silicon carbide semiconductor device includes: a silicon carbide semiconductor layer of a first conductivity type; a field insulating film formed on a surface of the silicon carbide semiconductor layer; a Schottky electrode formed on the surface of the silicon carbide semiconductor layer on an inner periphery side relative to the field insulating film, the Schottky electrode being formed to overlap onto the field insulating film; a front-surface electrode that covers the Schottky electrode and extends on the field insulating film beyond a peripheral edge of the Schottky electrode; and a terminal well region of a second conductivity type that is formed to be in contact with a part of the Schottky electrode in an upper part of the silicon carbide semiconductor layer and extends in the silicon carbide semiconductor layer on an outer periphery side relative to a peripheral edge of the front-surface electrode.

Abstract: According to one embodiment, a semiconductor device includes a first semiconductor region, a second semiconductor region, a third semiconductor region, and a first electrode. The first semiconductor region is of a first conductivity type. The second semiconductor region is provided on the first semiconductor region, and is of a second conductivity type. The third semiconductor region is provided on the second semiconductor region, and is of the second conductivity type. The third semiconductor region contains a first impurity of the first conductivity type and a second impurity of the second conductivity type, and satisfies 1<D2/D1<3, where D1 is a first concentration of the first impurity, and D2 is a second concentration of the second impurity. The first electrode is provided on the first, second, and third semiconductor regions. The first electrode is in contact with the second and third semiconductor regions.

Abstract: The present invention is to cause high channel mobility and a high threshold voltage to coexist in a SiC-MOSFET power device which uses a SiC substrate. The SiC MOSFET which is provided with a layered insulation film having electric charge trap characteristics on a gate insulation film has an irregular threshold voltage in a channel length direction of the SiC MOSFET, and in particular, has a shorter area having a maximum threshold voltage in the channel length direction compared to an area having other threshold voltages.

Abstract: This silicon carbide semiconductor device includes: a substrate with a principal surface; a silicon carbide layer which is arranged on a side of the principal surface of the substrate and which includes a first impurity region of a first conductivity type; a trench which is arranged in the silicon carbide layer and which has a bottom located in the first impurity region; a trench bottom impurity layer which is arranged in the trench to contact with at least a portion of the bottom of the trench and which is a silicon carbide epitaxial layer of a second conductivity type; a gate insulating film which covers a side surface of the trench and the trench bottom impurity layer; and a gate electrode which is arranged over at least a portion of the gate insulating film that is located inside the trench.

Abstract: Single crystal diamond having a high chemical purity i.e. a low nitrogen content and a high isotopic purity i.e. a low 13C content, methods for producing the same and a solid state system comprising such single crystal diamond are described.

Abstract: An electrode (109) insulated from a compound semiconductor layer (102) and being in contact with an electrode (101) and a compound semiconductor layer (103) is provided. A lattice constant of the compound semiconductor layer (103) is smaller than both of a lattice constant of the compound semiconductor layer (102) and a lattice constant of a compound semiconductor layer (104), and a lattice constant of a compound semiconductor layer (107) is smaller than both of the lattice constants of the compound semiconductor layer (102) and the lattice constants of the compound semiconductor layer (104). A conduction band energy of the compound semiconductor layer (103) is higher than a conduction band energy of the compound semiconductor layer (104).

Abstract: A semiconductor device is described, which includes a first transistor, a second transistor, and a capacitor. The second transistor and the capacitor are provided over the first transistor so as to overlap with a gate of the first transistor. A semiconductor layer of the second transistor and a dielectric layer of the capacitor are directly connected to the gate of the first transistor. The second transistor is a vertical transistor, where its channel direction is perpendicular to an upper surface of a semiconductor layer of the first transistor.

Abstract: According to one embodiment, a semiconductor device includes a structural body, an insulating film, and a control electrode. The structural body has a first surface, and includes a first semiconductor region including silicon carbide of a first conductivity type, a second semiconductor region including silicon carbide of a second conductivity type, and a third semiconductor region including silicon carbide of the first conductivity type. The structural body has a portion in which the first semiconductor region, the second semiconductor region, and the third semiconductor region are arranged in this order in a first direction along the first surface. The insulating film is provided on the first surface of the structural body. The control electrode is provided on the insulating film. The structural body has a buried region provided between the second semiconductor region and the first surface. The buried region is doped with a group V element.

Abstract: There is provided a silicon carbide semiconductor device allowing for suppression of breakage of an element upon short circuit of load. A MOSFET includes a silicon carbide layer, a gate insulating film, a gate electrode, a source electrode, and a drain electrode. The silicon carbide layer includes a drift region, a body region, and a source region. The MOSFET is configured such that a relational expression of n<?0.02RonA+0.7 is established in a case where a contact width of the source region and the source electrode is represented by n (?m) in a cross section in a thickness direction of the silicon carbide layer and a migration direction of carriers in the body region and where on resistance of the MOSFET in a state in which an inversion layer is formed in a channel region is represented by RonA (m?cm2).

Abstract: The semiconductor device according to the present invention includes: a semiconductor layer made of SiC; an impurity region formed by doping the semiconductor layer with an impurity; and a contact wire formed on the semiconductor layer in contact with the impurity region, while the contact wire has a polysilicon layer in the portion in contact with the impurity region, and has a metal layer on the polysilicon layer.

Abstract: Quality of a silicon carbide single crystal is improved. A crucible having first and second sides is prepared. A solid source material for growing silicon carbide with a sublimation method is arranged on the first side. A seed crystal made of silicon carbide is arranged on the second side. The crucible is arranged in a heat insulating container. The heat insulating container has an opening facing the second side. The crucible is heated such that the solid source material sublimes. A temperature on the second side is measured through the opening in the heat insulating container. The opening has a tapered inner surface narrowed toward the outside of the heat insulating container.

Abstract: Provided are methods of forming field effect transistors. The method includes preparing a substrate with a first region and a second region, forming fin portions on the first and second regions, each of the fin portions protruding from the substrate and having a first width, forming a first mask pattern to expose the fin portions on the first region and cover the fin portions on the second region, and changing widths of the fin portions provided on the first region.

Abstract: The present invention provides a semiconductor device in which the threshold voltage of NMOS and the threshold voltage of PMOS are independently controllable, and a method for fabricating the same. The method includes: forming a gate insulating film over an NMOS region and a PMOS region of a semiconductor substrate; forming a carbon-containing tungsten over the gate insulating film formed over one of the NMOS region and the PMOS region; forming a carbon-containing tungsten nitride over the gate insulating film formed over the other one of the PMOS region or the NMOS region; forming a tungsten film over the carbon-containing tungsten and the carbon-containing tungsten nitride; post-annealing the carbon-containing tungsten and the carbon-containing tungsten nitride; and etching the tungsten film, the carbon-containing tungsten, and the carbon-containing tungsten nitride, to form a gate electrode in the NMOS region and the PMOS region.

Abstract: A switching device includes a semiconductor layer, a graphene layer, a gate insulation layer, and a gate formed in a three-dimensional stacking structure between a first electrode and a second electrode formed on a substrate.

Abstract: Systems and methods for remote actuation of a downhole tool include a work string providing a flow path therein, a downhole tool coupled to the work string, at least one actuation device operatively coupled to the downhole tool and configured to act on the downhole tool such that the downhole tool performs a predetermined action, and an optical computing device communicably coupled to the at least one actuation device and configured to detect a characteristic of a substance in the flow path and trigger actuation of the at least actuation device when the characteristic is detected.

Abstract: A semiconductor device has a semiconductor substrate including a body region, a drift region, a trench that extends from a surface of the semiconductor substrate into the drift region through the body region, and a source region located adjacent to the trench in a range exposed to the surface of the semiconductor substrate, the source region being isolated from the drift region by the body region. A specific layer is disposed on a bottom of the trench, and it has a characteristic of forming a depletion layer at a junction between the specific layer and the drift region. An insulating layer covers an upper surface of the specific layer and a sidewall of the trench. A conductive portion is formed on a part of the side wall of the trench. The conductive portion is joined to the specific layer, and reaches the surface of the semiconductor substrate.

Abstract: A semiconductor device of the present disclosure includes a semiconductor layer provided on a main surface of a substrate. A cell region is provided with a gate insulating film disposed on the semiconductor layer and a gate electrode disposed on the gate insulating film, and a wiring region is provided with a field insulating film disposed on the semiconductor layer and a gate wire disposed on the field insulating film. An end of the field insulating film has a convex shape in a cross section perpendicular to the main surface of the substrate, and an upper surface of the field insulating film is rougher than an upper surface of a portion of the gate wire below which the field insulating film is not disposed.

Abstract: A method for fabricating the device includes patterning a first structure and a second structure on a semiconductor device. A first angled ion implantation is applied to the second structure such that the first structure is protected and a second angled ion implantation is applied to the first structure such that the second structure is protected, wherein exposed portions of the first and second structures have an altered rate of oxidation. Oxidation is performed to form thicker or thinner oxide portions on the exposed portions of the first and second structures relative to unexposed portions of the first and second structures. Oxide portions are removed to an underlying layer of the first and second structures. The first and second structures are removed. Spacers are formed about a periphery of remaining oxide portions. The remaining oxide portions are removed. A layer below the spacers is patterned to form integrated circuit features.

Abstract: A semiconductor structure includes a III-nitride substrate and a drift region coupled to the III-nitride substrate along a growth direction. The semiconductor substrate also includes a channel region coupled to the drift region. The channel region is defined by a channel sidewall disposed substantially along the growth direction. The semiconductor substrate further includes a gate region disposed laterally with respect to the channel region.

Abstract: In a manufacturing method of a silicon carbide semiconductor device, a semiconductor substrate made of single crystal silicon carbide is prepared. At a portion of the semiconductor substrate where a first electrode is to be formed, a metal thin film made of electrode material including an impurity is formed. After the metal thin film is formed, the first electrode including a metal reaction layer in which the impurity is introduced is formed by irradiating the metal thin film with a laser light.

Abstract: A method for manufacturing a semiconductor device includes (a) providing a silicon carbide semiconductor substrate; and (b) forming an electrode structure on the silicon carbide semiconductor substrate by (i) forming a Schottky layer including a metal selected from the group consisting of titanium, tungsten, molybdenum, and chrome on a front surface of the silicon carbide semiconductor substrate; (ii) heating the Schottky layer to form a Schottky electrode which has a Schottky contact with the silicon carbide semiconductor substrate; and (iii) forming a surface electrode comprised of aluminum or aluminum including silicon on a surface of the Schottky electrode, while heating at a temperature range effective for the surface electrode to closely cover any uneven portion of the Schottky electrode and provide a surface electrode having a predetermined reflectance that is equal to or less than 80% so that an improved recognition rate by an automatic wire bonding apparatus is obtained.

Abstract: Methods of forming and resulting devices are described that include graphene devices on boron nitride. Selected methods of forming and resulting devices include graphene field effect transistors (GFETs) including boron nitride.

Abstract: A method of forming a fine pattern includes forming first line mask patterns on a mask layer to extend along a direction, forming second line mask patterns to extend along a diagonal direction with respect to the first line mask patterns, anisotropically etching the mask layer exposed by the first and second line mask patterns to form elliptical openings, and isotropically etching the mask layer provided with the openings to form a mask pattern with enlarged openings.

Abstract: A semiconductor device includes a first silicon carbide semiconductor layer of a first conductive type that is positioned on a front surface of a substrate of the first conductive type, a transistor region that includes transistor cells, a Schottky region, and a boundary region. The boundary region includes a second body region and a gate connector that is arranged on the second body region via an insulating film and electrically connected with a gate electrode. The Schottky region includes a Schottky electrode that is arranged on the first silicon carbide semiconductor layer.

Abstract: The reliability of a semiconductor device including a power semiconductor element is improved. The basic idea in embodiments is to make the band gap of a cell region smaller than the band gap of a peripheral region. Specifically, a lower band gap region having a smaller band gap than the band gap of an epitaxial layer is formed in the cell region. In addition, a higher band gap region having a larger band gap than the band gap of the epitaxial layer is formed in the peripheral region.

Abstract: A silicon carbide device includes an epitaxial silicon carbide layer having a first conductivity type and a buried lateral silicon carbide edge termination region within the epitaxial silicon carbide layer and having a second conductivity type. The buried lateral silicon carbide edge termination region is covered by a silicon carbide surface layer including a doping of ions of a transition metal or including an increased density of intrinsic point defects in comparison to a density of intrinsic point defects of the buried lateral silicon carbide edge termination region.

Abstract: A method of manufacturing a semiconductor device includes the steps of: forming a semiconductor layer on a first main surface of a semiconductor substrate made of crystals having a wide band gap; forming lattice defects on a second main surface on a side opposite to the first main surface of the semiconductor substrate; and emitting a laser beam having a longer wavelength than an absorption edge wavelength which is a wavelength of a light having the lowest energy which the crystals absorb, to a lower surface of the semiconductor substrate after the step of forming the lattice defects; and forming an electrode on the second main surface of the semiconductor substrate after the step of emitting the laser beam.

Abstract: A semiconductor device includes a substrate and a plurality of transistors arranged on the substrate in an array. The transistor includes a first electrode, a plurality of second electrodes, and a gate electrode. The second electrodes are arranged around the first electrode. The gate electrode is located between the first electrode and the second electrodes. The first electrode is a polygon. The gate electrode is around the first electrode, and an edge of the gate electrode facing the first electrode has a shape corresponding to that of the first electrode. The first electrode and the edge of the gate electrode facing the first electrode are regular polygons, and have the same center.

Abstract: Silicon-carbon alloy structures can be formed as inverted U-shaped structures around semiconductor fins by a selective epitaxy process. A planarization dielectric layer is formed to fill gaps among the silicon-carbon alloy structures. After planarization, remaining vertical portions of the silicon-carbon alloy structures constitute silicon-carbon alloy fins, which can have sublithographic widths. The semiconductor fins may be replaced with replacement dielectric material fins. In one embodiment, employing a patterned mask layer, sidewalls of the silicon-carbon alloy fins can be removed around end portions of each silicon-carbon alloy fin. An anneal is performed to covert surface portions of the silicon-carbon alloy fins into graphene layers. In one embodiment, each graphene layer can include only a horizontal portion in a channel region, and include a horizontal portion and sidewall portions in source and drain regions.