Abstract: A method for manufacturing high-injection heterojunction bipolar transistor capable of being used as a photonic device is disclosed. A sub-collector layer is formed on a substrate. A collector layer is then deposited on top of the sub-collector layer. After a base layer has been deposited on top of the collector layer, a quantum well layer is deposited on top of the base layer. An emitter is subsequently formed on top of the quantum well layer.

Abstract: A semiconductor sensor determines physical and/or chemical properties of a medium, in particular a pH sensor. The semiconductor sensor has an electronic component with a sensitive surface, said component being constructed for its part on the basis of semiconductors with a large band gap (wide-gap semiconductor). The sensitive surface is provided at least in regions with a functional layer sequence which has an ion-sensitive surface. The functional layer sequence has at least one layer which is impermeable at least for the medium and/or the materials or ions to be determined.

Abstract: Provided are a heterojunction bipolar transistor and a method of forming the same.

Abstract: A semiconductor device may include a semiconductor buffer layer having a first conductivity type and a semiconductor mesa having the first conductivity type on a surface of the buffer layer. In addition, a current shifting region having a second conductivity type may be provided adjacent a corner between the semiconductor mesa and the semiconductor buffer layer, and the first and second conductivity types may be different conductivity types. Related methods are also discussed.

Abstract: The object of the present invention is to provide a heterojunction bipolar transistor with high breakdown tolerance which can be manufactured at a high reproducibility and a high yield, the heterojunction bipolar transistor includes: a sub-collector layer; a collector layer formed on the sub-collector layer; a base layer formed on the collector layer; and an emitter layer, which is formed on the base layer and is made of a semiconductor that has a larger bandgap than a semiconductor of the base layer, in which the collector layer includes: a first collector layer formed on the sub-collector layer; a second collector layer formed on the first collector layer; and a third collector layer formed between the second collector layer and the base layer, a semiconductor of the first collector layer differs from semiconductors of the third collector layer and the second collector layer, and an impurity concentration of the second collector layer is lower than an impurity concentration of the sub-collector layer and hi

Abstract: The present invention comprises a method for forming a semiconducting device including the steps of providing a layered structure including a substrate, a low diffusivity layer of a first-conductivity dopant; and a channel layer; forming a gate stack atop a protected surface of the channel layer; etching the layered structure selective to the gate stack to expose a surface of the substrate, where a remaining portion of the low diffusivity layer provides a retrograded island substantially aligned to the gate stack having a first dopant concentration to reduce short-channel effects without increasing leakage; growing a Si-containing material atop the recessed surface of the substrate; and doping the Si-containing material with a second-conductivity dopant at a second dopant concentration. The low diffusivity layer may be Si1-x-yGexZy, where Z can be carbon (C), xenon (Xe), germanium (Ge), krypton (Kr), argon (Ar), nitrogen (N), or combinations thereof.

Abstract: A method for forming a germanium-enriched region in a heterojunction bipolar transistor and a heterojunction bipolar transistor comprising a germanium-enriched region. A base having a silicon-germanium portion is formed over a collector. Thermal oxidation of the base causes a germanium-enriched region to form on a surface of the silicon-germanium portion subjected to the thermal oxidation. An emitter is formed overlying the germanium-enriched portion region. The germanium-enriched region imparts advantageous operating properties to the heterojunction bipolar transistor, including improved high-frequency/high-speed operation.

Abstract: The present invention provides an integrated semiconductor device that includes a semiconductor substrate, a first device containing a heterojunction bipolar transistor (HBT) located in a first region of the semiconductor substrate, wherein the HBT includes a base region containing a first portion of a SiGe or SiGeC layer, and a second device located in a second region of the semiconductor substrate, wherein the second device includes an interconnect containing a second portion of the SiGe or SiGeC layer. In a specific embodiment of the present invention, the second device is a memory device including a trench capacitor and a field effect transistor (FET) that are electrically connected together by the second portion of the SiGe or SiGeC layer. Alternatively, the second device is a trench-biased PNPN silicon controlled rectifier (SCR). The present invention also provides a novel reversibly programmable device or a novel memory device formed by a novel trench-biased SCR device.

Abstract: A method for enhancing operation of a bipolar light-emitting transistor includes the following steps: providing a bipolar light-emitting transistor having emitter, base, and collector regions; providing electrodes for coupling electrical signals with the emitter, base, and collector regions; and adapting the base region to promote carrier transport from the emitter region toward the collector region by providing, in the base region, several spaced apart quantum size regions of different thicknesses, with the thicknesses of the quantum size regions being graded from thickest near the collector to thinnest near the emitter.

Abstract: Methods of fabricating semiconductor devices using electrode-less wet-etching techniques to reduce defect densities on etched group III-nitride semiconductor surfaces are described herein. The methods generally involve contacting an etched surface of a component of a semiconductor device with a solution comprising a metal hydroxide and an oxidizing agent effective to reduce a roughness of the etched surface, wherein the etched surface is formed from a composition comprising a nitride of a group III element. Improved semiconductor devices are also disclosed.

Abstract: Provided are a hetero-junction bipolar transistor (HBT) that can increase data processing speed and a method of manufacturing the hetero-junction bipolar transistor.

Abstract: A wafer comprising at least one emitter-up Heterojunction Bipolar Transistor (HBT) and at least one emitter-down HBT on a common InP based semiconductor wafer. Isolation and N-type implants into the device layers differentiate an emitter-down HBT from an emitter-up HBT. The method for preparing a device comprises forming identical layers for all HBTs and performing ion implantation to differentiate an emitter-down HBT from an emitter-up HBT.

Abstract: The invention concerns a heterojunction bipolar transistor comprising a support, and epitaxially grown from said support, at least: one collecting, respectively emitting, layer; at least one base layer; and at least one emitting, respectively collecting, layer. The collecting, respectively emitting, layer comprises: at least one first undercoat contacted with said base layer, substantially of similar composition as said emitting, respectively collecting, layer; and at least one second undercoat on the side opposite said base layer relative to said first undercoat.

Abstract: A transistor having minimized parasitics is provided including an emitter having a recessed extrinsic emitter portion atop an intrinsic emitter portion; a base including an intrinsic base portion in electrical contact with the intrinsic emitter portion and an extrinsic base portion in electrical contact with the intrinsic base portion and electrically isolated from the recessed extrinsic emitter portion by a set of emitter/base spacers; and a collector in electrical contact with the intrinsic base portion. The transistor may further include extrinsic base having top surfaces entirely silicided to the emitter/base spacer. Additionally, the transistor may include a base window opening within the transistor's active area. Methods of forming the above-described transistor are also provided.

Abstract: Provided is a process for forming a contact for a compound semiconductor device without electrically shorting the device. In one embodiment, a highly doped compound semiconductor material is electrically connected to a compound semiconductor material of the, same conductivity type through an opening in a compound semiconductor material of the opposite conductivity type. Another embodiment discloses a transistor including multiple compound semiconductor layers where a highly doped compound semiconductor material is electrically connected to a compound semiconductor layer of the same conductivity type through an opening in a compound semiconductor layer of the opposite conductivity type. Embodiments further include metal contacts electrically connected to the highly doped compound semiconductor material. A substantially planar semiconductor device is disclosed. In embodiments, the compound semiconductor material may be silicon carbide.

Abstract: A bipolar transistor (1) comprising a subcollector layer (3), a collector layer (4, 5), a base layer (6) and an emitter layer (7) which are successively built up and having: the subcollector layer (3) formed with a projection (3A) and recesses (3B), an upper part above the projection constituting an intrinsic transistor region (1A) of the bipolar transistor; insulator layer (10) buried between the recesses of the subcollector layer and the collector layer (4); a boundary interface between the subcollector layer and the collector layer held between the insulator layers; the base layer (6) made of a single crystal layer and provided with a base electrode (12) on a region becoming an extrinsic base layer (6B) of the base layer; and the subcollector layer provided with a collector electrode (11). The bipolar transistor has advantages of its emitter made finer in width, a reduced parasitic capacitance between its base and collector and improved high-frequency characteristics.

Abstract: A heterojunction bipolar transistor (HBT) device and system having electrostatic discharge ruggedness, and methods for making the same, are disclosed. An HBT device having electrostatic discharge ruggedness may include one or more emitter fingers including an emitter layer, a transition layer formed over the emitter layer, and an emitter cap layer formed over the transition layer.

Abstract: Embodiments of the present invention provide a bipolar transistor with low resistance base contact and method of manufacturing the same. The bipolar transistor includes an emitter, a collector, and an intrinsic base between the emitter and the collector. The intrinsic base extends laterally to an extrinsic base. The extrinsic base further includes a first semiconductor material with a first bandgap and a second semiconductor material with a second bandgap that is smaller than the first bandgap.

Abstract: A bipolar transistor includes a base layer design and a method for fabricating such a bipolar transistor that employ a built-in accelerating field focused on a base region adjacent to a collector, where minority carrier transport is otherwise retarded. The accelerating field of the base layer includes on average, a relatively low p-doping level in a first region proximate to the collector and a relatively high p-doping level in a second region proximate to an emitter. Alternatively, the accelerating field can be derived from band gap grading, wherein the grade of band gap in the first region is greater than the grade of band gap in the second region, and the average band gap of the first region is lower than that of the second region.

Abstract: An object of the present invention is to provide a semiconductor device and a manufacturing method thereof which can realize a normally-off field-effect transistor made of a III group nitride semiconductor. The present invention includes: placing a sapphire substrate in a crystal growth chamber; forming a low-temperature GaN buffer layer made of GaN as the III group nitride semiconductor, on a main surface of the sapphire substrate by a MOCVD method; and forming a GaN layer on the low-temperature GaN buffer layer by the MOCVD method. Here, a [11-20] axis of the GaN layer is perpendicular to the main surface of the sapphire substrate.

Abstract: The present invention relates to a high performance heterojunction bipolar transistor (HBT) having a base region with a SiGe-containing layer therein. The SiGe-containing layer is not more than about 100 nm thick and has a predetermined critical germanium content. The SiGe-containing layer further has an average germanium content of not less than about 80% of the predetermined critical germanium content. The present invention also relates to a method for enhancing carrier mobility in a HBT having a SiGe-containing base layer, by uniformly increasing germanium content in the base layer so that the average germanium content therein is not less than 80% of a critical germanium content, which is calculated based on the thickness of the base layer, provided that the base layer is not more than 100 nm thick.

Abstract: In one embodiment, the invention is a method and apparatus for fabricating a heterojunction bipolar transistor. One embodiment of a heterojunction bipolar transistor includes a collector layer, a base region formed over the collector layer, a self-aligned emitter formed on top of the base region and collector layer, a poly-germanium extrinsic base surrounding the emitter, and a metal germanide layer formed over the extrinsic base.

Abstract: The invention relates to a semiconductor device with a substrate (11) and a semiconductor body (11) comprising a bipolar transistor with an emitter region (1), a base region (2) and a collector region (3) comprising a first, a second and a third connection conductor, which emitter region (1) comprises a mesa-shaped emitter connection region (1A) provided with spacers (4) and adjacent thereto a base connection region (2A) comprising a conductive region (2AA) of poly crystalline silicon. In a device (10) according to the invention, the base connection region (2A) comprises a further conducting region (2AB), which is positioned between the conductive region (2AA) of poly crystalline silicon and the base region (2) and which is made of a material with respect to which the conducting region (2AA) of polycrystalline silicon is selectively etchable. Such a device (10) is easy to manufacture by means of a method according to the invention and its bipolar transistor possesses excellent RF properties.

Abstract: A method for forming an epitaxial base layer in a bipolar device. The method comprises the steps of: providing a structure having a field isolation oxide region (12) adjacent to an active silicon region (10); forming a silicon nitride/silicon stack (14, 16) above the field isolation oxide region (12), wherein the silicon nitride/silicon stack (14, 16) includes a top layer of silicon (14) and a bottom layer of silicon nitride (16); performing an etch to the silicon nitride/silicon stack (14, 16) to form a stepped seed layer, wherein the top layer of silicon is etched laterally at the same time the bottom layer of silicon nitride is etched; and growing an Si/SiGe/Si stack (20) over the stepped seed layer and active region (10).

Abstract: A base mesa finger (an emitter ledge layer 15, a base layer 16, and a collector layer 17) is interposed between two collector fingers (collector electrodes 13), and on the base mesa finger, a base finger (a base electrode 12) and two emitter fingers (an emitter layer 14 and an emitter electrode 11) on both sides of the base finger, are formed. The two emitter fingers are formed symmetric with respect to the base finger as a reference.

Abstract: A semiconductor device provided with an emitter layer having a narrowed base contact portion. The semiconductor device includes a collector layer arranged on a semiconductor substrate. A conductive layer is arranged on the collector layer. A silicon film is arranged on the conductive layer. An emitter electrode is arranged on the silicon film. A first film covers the side of the emitter electrode. The silicon film includes a first region contacting the emitter electrode and a second region differing from the first region. A contact surface between the first region and the emitter electrode is located at a level that is higher than that of the lower surface of the first film. At least part of the second region of the silicon film is located between the conductive layer and the first film and is in contact with the conductive layer and the first film.

Abstract: Embodiments herein present a structure, method, etc. for a self-alignment scheme for a heterojunction bipolar transistor (HBT). An HBT is provided, comprising an extrinsic base, a first self-aligned silicide layer over the extrinsic base, and a nitride etch stop layer above the first self-aligned silicide layer. A continuous layer is also included between the first self-aligned silicide layer and the nitride etch stop layer, wherein the continuous layer can comprise oxide. The HBT further includes spacers adjacent the continuous layer, wherein the spacers and the continuous layer separate the extrinsic base from an emitter contact. In addition, an emitter is provided, wherein the height of the emitter is less than or equal to the height of the extrinsic base. Moreover, a second self-aligned silicide layer is over the emitter, wherein the height of the second silicide layer is less than or equal to the height of the first silicide layer.

Abstract: Hetero-epitaxial semiconductor materials comprising cubic crystalline semiconductor alloys grown on the basal plane of trigonal and hexagonal substrates, in which misfit dislocations are reduced by approximate lattice matching of the cubic crystal structure to underlying trigonal or hexagonal substrate structure, enabling the development of alloyed semiconductor layers of greater thickness, resulting in a new class of semiconductor materials and corresponding devices, including improved hetero-bipolar and high-electron mobility transistors, and high-mobility thermoelectric devices.

Abstract: A transistor having minimized parasitics is provided including an emitter having a recessed extrinsic emitter portion atop an intrinsic emitter portion; a base including an intrinsic base portion in electrical contact with the intrinsic emitter portion and an extrinsic base portion in electrical contact with the intrinsic base portion and electrically isolated from the recessed extrinsic emitter portion by a set of emitter/base spacers; and a collector in electrical contact with the intrinsic base portion. The transistor may further include extrinsic base having top surfaces entirely silicided to the emitter/base spacer. Additionally, the transistor may include a base window opening within the transistor's active area. Methods of forming the above-described transistor are also provided.

Abstract: According to one exemplary embodiment, a heterojunction bipolar transistor includes a base situated on a substrate. The heterojunction bipolar transistor can be an NPN silicon-germanium heterojunction bipolar transistor, for example. The heterojunction bipolar transistor further includes a cap layer situated on the base, where the cap layer includes a barrier region. The barrier region can comprises carbon and has a thickness, where the thickness of the barrier region determines a depth of an emitter-junction of the heterojunction bipolar transistor. An increase in the thickness of the barrier region can cause a decrease in the depth of the emitter-base junction. According to this exemplary embodiment, the heterojunction bipolar transistor further includes an emitter situated over the cap layer, where the emitter comprises an emitter dopant, which can be phosphorus. A diffusion retardant in the barrier region of the cap layer impedes diffusion of the emitter dopant.

Abstract: Disclosed is a design structure for an improved semiconductor structure (e.g., a silicon germanium (SiGe) hetero-junction bipolar transistor) having a narrow essentially interstitial-free SIC pedestal with minimal overlap of the extrinsic base. Also, disclosed is a method of forming the transistor which uses laser annealing, as opposed to rapid thermal annealing, of the SIC pedestal to produce both a narrow SIC pedestal and an essentially interstitial-free collector. Thus, the resulting SiGe HBT transistor can be produced with narrower base and collector space-charge regions than can be achieved with conventional technology.

Abstract: In one example embodiment, an integrated semiconductor circuit (400) is provided. The integrated circuit (400) comprises a substrate (430) comprising a first material and a first electronic device (455) comprising a first depressed region (415) within the substrate (430) and a set of first device contact locations (475) in a contact level (300). The integrated circuit (400) further comprises a second electronic device 450 comprising a set of second device contact locations (451) in the contact level (300) and a second material (420) in the first depressed (415) region having a lattice mismatch with the first material.

Abstract: A unit HBT and a unit FET are arranged to be adjacent to each other through an isolation region and a base electrode of the unit HBT is connected to a source electrode of the unit FET to form a unit element, and a plurality of unit elements are connected to form an active element. This makes it possible to implement the active element in which a current is not likely to concentrate on the unit element and no destruction is generated by the second breakdown. Moreover, although a buried gate electrode structure is used to ensure a withstand pressure in the unit FET, a buried portion is structured not to be diffused to an InGaP layer, and thereby it is possible to prevent Pt from being abnormally diffused. Furthermore, a selection etching can be used for a formation of an emitter mesa, that of a base mesa, that of a ledge in the unit HBT, and a gate recess etching in the unit FET, and a good reproducibility can be obtained.

Abstract: A semiconductor device with ohmic contact is provided with a method of making the same. In one embodiment, a method is provided for fabricating a semiconductor device. The method comprises providing a semiconductor structure with a N-type doped semiconductor contact layer, forming a platinum contact portion over the N-type doped semiconductor contact layer, forming an adhesive contact portion over the platinum contact portion, forming a barrier contact portion over the adhesive contact portion, and forming a gold contact portion over the barrier contact portion. The method further comprises annealing the semiconductor structure to alloy the platinum contact portion with the N-type doped semiconductor contact layer to form a platinum/semiconductor alloyed diffusion contact barrier substantially disposed within the N-type doped semiconductor contact layer.

Abstract: According to one exemplary embodiment, a heterojunction bipolar transistor includes a base situated on a substrate. The heterojunction bipolar transistor can be an NPN silicon-germanium heterojunction bipolar transistor, for example. The heterojunction bipolar transistor further includes a cap layer situated on the base, where the cap layer includes a barrier region. The barrier region can comprises carbon and has a thickness, where the thickness of the barrier region determines a depth of an emitter-junction of the heterojunction bipolar transistor. An increase in the thickness of the barrier region can cause a decrease in the depth of the emitter-base junction. According to this exemplary embodiment, the heterojunction bipolar transistor further includes an emitter situated over the cap layer, where the emitter comprises an emitter dopant, which can be phosphorus. A diffusion retardant in the barrier region of the cap layer impedes diffusion of the emitter dopant.

Abstract: The disclosure relates to a method for forming an intermediate lattice transition buffer layer. The method includes: (a) depositing a first graded InAlAs layer on a substrate at a first constant temperature, the first graded InAlAs layer having an In/AI composition ratio which increases across the buffer layer from a first level to a second level; (b) annealing at least the first graded InAlAs layer; (c) depositing the second graded InAlAs layer on the first graded InAlAs layer at the first constant temperature, the second graded InAlAs layer having an In/Al composition ratio which increases across the buffer layer from the second level to a third level; and (d) annealing at least the second graded InAlAs layer; the buffer layer being formed under Groups III/V overpressure.

Abstract: Methods of making Si-containing films that contain relatively high levels of substitutional dopants involve chemical vapor deposition using trisilane and a dopant precursor. Extremely high levels of substitutional incorporation may be obtained, including crystalline silicon films that contain 2.4 atomic % or greater substitutional carbon. Substitutionally doped Si-containing films may be selectively deposited onto the crystalline surfaces of mixed substrates by introducing an etchant gas during deposition.

Abstract: A semiconductor device is provided. In one example, a semiconductor device has a D-HBT structure which include a base layer formed from InGaAs and an emitter layer and a collector layer both formed from InGaP in such a way as to hold said base layer between them, wherein said InGaAs has a composition such that the content of In is smaller than 53% and said InGaP has a composition such that the content of In is just enough to make the lattice constant of said emitter layer and collector layer equal to the lattice constant of said base layer. This semiconductor device realizes a large current gain while keeping the high-speed operation owing to the base layer of InGaAs having good carrier mobility. In addition, it can be formed on a large wafer as the substrate.

Abstract: This invention provides methods for fabricating thin film electronic devices with both front- and backside processing capabilities. Using these methods, high temperature processing steps may be carried out during both frontside and backside processing. The methods are well-suited for fabricating back-gate and double-gate field effect transistors, double-sided bipolar transistors and 3D integrated circuits.

Abstract: A nitride-based group III-V compound semiconductor device includes a buffer layer, a first nitride semiconductor layer and a second nitride semiconductor layer successively stacked on a substrate, the first and the second nitride layers having their respective lattice constants a1 and a2 in the relation a1>a2, an ohmic source electrode and an ohmic drain electrode formed on the second nitride layer, and a piezoelectric effect film formed on at least a partial region between the electrodes, wherein the piezoelectric film exerts compressive stress of an absolute magnitude at least equivalent to that of tensile stress applied to the second nitride layer due to the difference (a1?a2) between the lattice constants of the first and second nitride layers.

Abstract: A semiconductor device includes an emitter layer: a base layer; and a collector layer, wherein the collector layer and the emitter layer each include a heavily doped thin sublayer having a high impurity concentration, and each of the heavily doped thin sublayers has an impurity concentration higher than those of semiconductor layers adjacent to each heavily doped thin sublayer.

Abstract: A method of forming a semiconductor device is disclosed. The method includes providing a floor for a semiconductor device by utilizing a CMOS process. The method further includes providing a BiCMOS-like process on top of the floor to further fabricate the semiconductor device, wherein the BiCMOS-like process and the CMOS process provides the semiconductor device.

Abstract: On a high-concentration n-type first sub-collector layer, a high-concentration n-type second sub-collector layer made of a material having a small bandgap, an i-type or low-concentration n-type collector layer, a high-concentration p-type base layer, an n-type emitter layer made of a material having a large bandgap, a high-concentration n-type emitter cap layer, a high-concentration n-type emitter contact layer made of a material having a small bandgap are sequentially stacked. From the emitter contact layer, an interconnection also serving as an emitter electrode is extended. From the emitter layer or the base layer, an interconnection also serving as a base electrode is extended. From the second sub-collector layer, an interconnection also serving as a collector electrode is extended.

Abstract: A hetero-bonded SOI substrate comprises a stack of a semiconductor handle substrate, an isolation insulator layer, a depinning dielectric layer, and a top non-silicon semiconductor layer. The depinning layer abuts both the top non-silicon semiconductor layer and the isolation insulator layer and relaxes Fermi level pinning in the top non-silicon semiconductor layer. The top non-silicon semiconductor layer may be a III-V compound semiconductor layer such as GaAs and the depinning dielectric layer may be a (GdxGa1-x)2O3 layer. The interface defect density may be reduced below 5.0×1011 cm?2 eV?1.

Abstract: A metal-base transistor is suggested. The transistor comprises a first and a second electrode (2, 6) and base electrode (6) to control current flow between the first and second electrode. The first electrode (2) is made from a semiconduction material. The base electrode (3) is a metal layer deposited on top of the semiconducting material forming the first electrode. According the invention the second electrode is formed by a semiconducting nanowire (6) being in electrical contact with the base electrode (3).

Abstract: A base layer made of SiGe mixed crystal includes a spacer layer formed in contact with a collector layer with no base impurities diffused therein and an intrinsic base layer formed in contact with an emitter layer with base impurities diffused therein. The spacer layer contains C at a low concentration. The intrinsic base layer has a first region containing C at a low concentration on the collector side and a second region containing C at a high concentration on the emitter side.

Abstract: A field-effect transistor is provided which includes: a first nitride semiconductor layer having a lattice constant a1 and a bandgap Eg1; a second nitride semiconductor layer stacked on the first nitride semiconductor layer and having a lattice constant a2 and a bandgap Eg2; a source electrode and a drain electrode formed on the second nitride semiconductor layer; a piezo-effect film formed on the second nitride semiconductor layer in a region between the source electrode and the drain electrode; and a gate electrode formed on a region of the piezo-effect film. The relation between the lattice constants a1 and a2 is a1>a2. The relation between the bandgaps Eg1 and Eg2 is Eg1<Eg2.

Abstract: A semiconductor device includes a support substrate and a semiconductor layer formed on the underlying substrate. The support substrate has its metal part formed by plating and extending across its entire thickness, whilst it has the other region made of semiconductor part. In particular, the region of the support substrate lying immediately below an active region is the metal part formed by plating. The region of the support substrate lying immediately below the region other than the active region is an inactive region made of semiconductor. The semiconductor device thus suppresses warping of a substrate otherwise caused by stress in the metal part formed by plating, and heat evolved due to the current in operation of the semiconductor device may be dissipated over the shortest path through the metal part having a higher thermal conductivity.

Abstract: A metamorphic buffer layer is formed on a semi-insulating substrate by an epitaxial growth method, a collector layer, a base layer, an emitter layer and an emitter cap layer are sequentially laminated on the metamorphic buffer layer, and a collector electrode is provided in contact with an upper layer of the metamorphic buffer layer. The metamorphic buffer layer is doped with an impurity, in a concentration equivalent to or higher than that in a conventional sub-collector layer, by an impurity doping process during crystal growth so that the metamorphic buffer layer will be able to play the role of guiding the collector current to the collector electrode. Since the sub-collector layer, which is often formed of a ternary mixed crystal or the like having a high thermal resistance, can be omitted, the heat generated in the semiconductor device can be rapidly released into the substrate.

Abstract: A method for forming a germanium-enriched region in a heterojunction bipolar transistor and a heterojunction bipolar transistor comprising a germanium-enriched region. A base having a silicon-germanium portion is formed over a collector. Thermal oxidation of the base causes a germanium-enriched region to form on a surface of the silicon-germanium portion subjected to the thermal oxidation. An emitter is formed overlying the germanium-enriched portion region. The germanium-enriched region imparts advantageous operating properties to the heterojunction bipolar transistor, including improved high-frequency/high-speed operation.