Abstract: A hetero-junction FET has an intermediate layer including n-type-impurity doped layer between an electron supply layer and an n-type cap layer. The intermediate layer cancels the polarized negative charge generated between the electron supply layer and the n-type cap layer by ionized positive charge, thereby reducing the barrier against the electrons and source/drain resistance.

Abstract: A GaN-based high electron mobility transistor (HEMT) has an undoped GaN layer where a two-dimensional electron gas layer is formed, the undoped GaN layer having a high electric resistivity enabling a pinch-off state to be obtained even when the gate bias voltage is 0 V. The GaN-based HEMT comprises a semi-insulating substrate on which a GaN buffer layer is formed. An undoped GaN layer is disposed on the GaN buffer layer and has an electric resistivity of not less than 1×106 &OHgr;/cm2. An undoped AlGaN layer is disposed on the undoped GaN layer via a heterojunction such that an undercut portion is formed therebetween. An n-type GaN layer is further disposed in such a manner as to bury side portions of the undoped AlGaN layer and the undercut portion. The individual layers thus form a layered structure. A gate electrode G is formed on the undoped AlGaN layer, and a source electrode S and a drain electrode D are formed on the n-type GaN layer.

Abstract: An integrated circuit for intermediate impedance matching and stabilization of high power devices is disclosed. High quality epitaxial layers of monocrystalline materials grown over monocrystalline substrates enables the formation of impedance matching and stability circuits to be placed on the same substrate as the active device. Additionally, by using the manifolds of the active to form plates of a capacitor, an impedance matching network of series inductance and shunt capacitor can be compactly fabricated for increasing the output impedance to intermediate levels. The manifolds of the active device are also used to form capacitors to provide stability to high power active devices.

Abstract: An integrated circuit for intermediate impedance matching and stabilization of high power devices is disclosed. High quality epitaxial layers of monocrystalline materials grown over monocrystalline substrates enables the formation of impedance matching and stability circuits to be placed on the same substrate as the active device. Additionally, by using the manifolds of the active to form plates of a capacitor, an impedance matching network of series inductance and shunt capacitor can be compactly fabricated for increasing the output impedance to intermediate levels. The manifolds of the active device are also used to form capacitors to provide stability to high power active devices.

Abstract: High-speed and low-power-consuming transistors such as field effect transistors having strained Si channels and hetero-bipolar transistors are integrated with each other. Used here is a complex structure in which an MOSFET having a thin-film SiGe buffer layer and a strained Si channel are laminated on an insulating film and an HBT having an SiGe base layer formed on a thin-film SiGe layer by epitaxial growth and an Si emitter layer formed on the SiGe base layer are combined with each other. The thin-film SiGe layer formed on the insulating film of the MOSFET is made thinner than the counterpart of the HBT. The thin-film SiGe layer formed on the insulating film of the MOSFET has Ge concentration higher than that of the counterpart of the HBT.

Abstract: A semiconductor device includes a semiconductor layer structure, and gate, drain and source electrodes provided on the semiconductor layer structure, the gate electrode being located between the drain and source electrodes. A depletion modulating part is located between the gate electrode and the drain electrode and includes portions spaced apart from each other in a gate-width direction.

Abstract: Two or more coupled sub-wells are inserted in the quantum well region of a MODFET to move the electron/hole gas away from the interface between the spacer layer and the well region. The channel can be constructed with a wire cross-section to confine the electron/hole gas in two dimensions, thereby reducing the scattering and improving the device performance. Structures with supply layer contacts, along with their application are described. Laterally coupled quantum wire MODFETs are also disclosed. The insertion of a coupled-well transport channel is applicable for Si MOSFETs in improving the high frequency performance.

Abstract: A semiconductor switching device of mirror logic includes two FETs having a gate width of 600 &mgr;m, a common input terminal, two control terminal and two output terminals. The resistors connecting the control terminals and the gate electrodes of FETs are placed underneath a pad metal layer extending from the common input terminal. Both FETs extend into the space between the control terminals and the output terminals. The device can be housed in the same package as the device of non-mirror logic.

Abstract: A hybrid integrated circuit includes a monocrystalline accommodating layer positioned between a monocrystalline substrate and a compound semi-conductor layer. Electronic circuitry may be embedded in both the monocrystalline substrate and the compound semiconductor layer. Internal circuitry may be formed in either of these regions while an associated I/O structure is formed in the other region. Use of the invention allows circuits that are formed using either structure to easily communicate with external devices that are more suited for communication with circuits that are formed using another structure.

Abstract: A high electron mobility transistor (HEMT) (10) is disclosed that includes a semi-insulating silicon carbide substrate (11), an aluminum nitride buffer layer (12) on the substrate, an insulating gallium nitride layer (13) on the buffer layer, an active structure of aluminum gallium nitride (14) on the gallium nitride layer, a passivation layer (23) on the aluminum gallium nitride active structure, and respective source, drain and gate contacts (21, 22, 23) to the aluminum gallium nitride active structure.

Abstract: A family of high speed transistors and optoelectronic devices is obtained on a monolithic substrate with an epitaxial layer structure comprised of two modulation doped transistor structures, one inverted with respect to the other. The transistor structures are obtained by modification of the Pseudomorphic High Electron Mobility Transistor (PHEMT) structure and are combined in a unique way to create a thyristor structure. The thyristor structure may be used as a digital modulator, a transceiver, an amplifier and a directional coupler. These devices may be realized as either waveguide or vertical cavity devices. The vertical cavity construction enables resonant cavity operation of all device modes. In addition to the multiple optoelectronic properties, the structure also produces inversion channel bipolar devices termed BICFETs having either electrons or holes as the majority carrier and heterostructure FETs with both electron and hole channels.

Abstract: A method of fabricating apparatus, and the apparatus, for providing low voltage temperature compensation in a single power supply HFET including a stack of epitaxially grown compound semiconductor layers with an HFET formed in the stack. A Schottky diode is formed in the stack adjacent the HFET during the formation of the HFET. The HFET and the Schottky diode are formed simultaneously, with a portion of one of the layers of metal forming the gate of the HFET being positioned in contact with a layer of the stack having a low bandgap (e.g. less than 0.8 eV) to provide a turn-on voltage for the Schottky diode of less than 1.8 Volts. The Schottky diode is connected to the gate contact of the HFET by a gate circuit to compensate for changes in current loading in the gate circuit with changes in temperature.

Abstract: A p-type layer and an n-type layer which constitute a barrier layer are provided, and a leak of the holes at the time of the negative bias accompanying the p-type layer buffer required for the higher tolerance voltage is suppressed, and the discharge of the holes at the positive bias can be efficiently carried out. The tolerance voltage at the time of the OFF state is raised at the p-type layer buffer, and the tolerance voltage at the time of the ON state at the discharge of the holes is raised. Since no leak is generated from the p-type layer, the drain current is not lowered, and a higher output can be realized both in terms of the current and in terms of the voltage.

Abstract: It is an object of the present invention to provide a radio frequency module incorporating an MMIC that has a high S/N ratio while ensuring a high output. A radio frequency module according to the present invention incorporates an MMIC having a field effect transistor in which channel layers for traveling of carriers are formed by a heterostructure of two or more different kinds of materials, and height of a potential barrier of an interface between the different kinds of materials is less than 0.22 eV.

Abstract: A high-breakdown-voltage semiconductor device has a first offset layer and a second offset layer the dosage of which is higher than that of the first offset layer. When the gate is in the ON state, the first offset layer functions as a resurf layer. When the gate is in the OFF state, part of the charge in the first offset layer is neutralized by a drain current flowing through an element having a low ON-resistance, however, the second offset layer functions as a resurf layer. When the drain current is [Acm−1], the amount of charge of electrons is q[C], and the drift speed of carriers is &ugr;drift[cms−1], the dosage n2 of the second offset layer is given by n2≧ID/(q &ugr;drift) [cms−2].

Abstract: Using a mask opening a gate region, an undoped GaAs layer is selectively etched with respect to an undoped Al0.2Ga0.8As layer by dry etching with introducing a mixture gas of a chloride gas containing only chlorine and a fluoride gas containing only fluorine (e.g. BCl3+SF6 or so forth). By about 100% over-etching is performed for the undoped GaAs layer, etching (side etching) propagates in transverse direction of the undoped GaAs layer. With using the mask, a gate electrode of WSi is formed. Thus, a gap in a width of about 20 nm is formed by etching in the transverse direction on the drain side of the gate electrode. By this, a hetero junction FET having reduced fluctuation of characteristics of an FET, such as a threshold value, lower rising voltage and higher breakdown characteristics is obtained.

Abstract: In order to reduce a contact resistance of an electrode of a semiconductor device, a metal layer is directly formed on a source area and a drain area so as to form a source electrode and a drain electrode without providing a cap layer thereunder. Consequently, a step for removing the cap layer can be eliminated, simplifying the manufacturing process for the semiconductor device.

Abstract: A semiconductor device operable with a single positive power source, enabling an increase in efficiency, and improved in high-frequency characteristics by lowering the resistivity of a gate contact, including a carrier run layer formed on a substrate for running of carriers; a carrier supply layer formed on the carrier run layer, having a larger bandgap than the carrier run layer, and containing a first conductivity type impurity; a barrier layer formed on the carrier supply layer and having a smaller bandgap than the carrier supply layer; a source electrode and a drain electrode formed on the barrier layer at a predetermined distance from each other; a gate electrode formed on the barrier layer between the source electrode and the drain electrode away from the source electrode and the drain electrode; and a first low resistivity region formed at least below the gate electrode in the barrier layer and containing a second conductivity type impurity opposite in conductivity to the first conductivity type, and a

Abstract: A semiconductor device having a bipolar transistor which is capable of high integration, and a semiconductor device in which the bipolar transistor has good characteristic properties. A process for producing said semiconductor device.

Abstract: A semiconductor device comprises an electrically conductive III-V semiconductor substrate which has mutually opposite first and second main surfaces. At least one pn junction, reverse biased during operation of the semiconductor device, is disposed above the first main surface. At least one functional semiconductor structure is disposed above the at least one pn junction. The functional semiconductor structure is electrically insulated from the second main surface of the III-V semiconductor substrate.

Abstract: There is provided a hetero-junction field effect transistor including (a) a first semiconductor layer composed of InP, (b) a second semiconductor layer formed on the first semiconductor layer, the second semiconductor layer having a smaller electron affinity than that of the first semiconductor layer, (c) a third semiconductor layer formed on the second semiconductor layer, the third semiconductor layer having a greater electron affinity than that of the second semiconductor layer, and being formed at a surface thereof with an opening, the third semiconductor layer being composed of InP, (d) source and drain electrodes formed on the third semiconductor layer, and (e) a gate electrode formed on the second semiconductor layer in the opening of the third semiconductor layer. In accordance with the hetero-junction field effect transistor, it is possible to enhance noise characteristic and high power characteristic.

Abstract: When a device using GaN semiconductors is made on a hard and chemically stable single-crystal substrate such as sapphire substrate or SiC substrate, a semiconductor device and its manufacturing method ensure high-power output or high-frequency operation of the device by thinning the substrate or making a via hole in the substrate. When a light emitting device using GaN semiconductors is made on a non-conductive single-crystal substrate such as sapphire substrate, the semiconductor device and its manufacturing method reduce the operation voltage of the light emitting device by making a via hole to the substrate. More specifically, after making a GaN FET by growing GaN semiconductor layers on the surface of a sapphire substrate, the bottom surface of the sapphire substrate is processed by lapping, using an abrasive liquid containing a diamond granular abrasive material and reducing the grain size of the abrasive material in some steps, to reduce the thickness of the sapphire substrate to 100 &mgr;m or less.

Abstract: The invention is a Pseudomorphic transistor structure having a semiconductor layer having a 2DEG layer therein, a Schottky layer, a transition layer and an ohmic contact layer on the transition layer, wherein a double recess structure is disposed through the ohmic layer onto the transition layer in which one or two layers of InyGa1−yP are used as etch-stop layers to define the depth of the recess.

Abstract: A semiconductor device includes a Schottky layer, a cap layer covering the surface of the Schottky layer, and a Schottky electrode of a two-level structure. The Schottky electrode has a lower portion that penetrates through the cap layer and reaches the Schottky layer, and has an upper portion larger than the lower portion in cross-sectional area and that overlies the cap layer. With this construction, surface defects are unlikely to occur, so that a highly reliable semiconductor device can be fabricated.

Abstract: An electrode having a good contact between a semiconductor substrate and an electrode film is formed in a semiconductor device, and a manufacturing method therefor. On first AlGaAs of a compound semiconductor substrate, a second semiconductor layer of second AlGaAs formed with p-type impurity region is formed, a third semiconductor layer of low resistance GaAs and AlGaAs having a band gap narrower than that of the second semiconductor layer is formed thereon and, further, an electrode film is formed on the third semiconductor layer.

Abstract: The impurity concentration contained in a layer on an electron supply layer of a high electron mobility field effect transistor is set in the range of 1×1016 to 1×1017 atoms/cm3, or the bandgap of a Schottky layer is set wider than that of the electron supply layer.

Abstract: A transistor structure is provided. This structure has a source electrode and a drain electrode. A doped cap layer of GaxIn1−xAs is disposed below the source electrode and the drain electrode and provides a cap layer opening. An undoped resistive layer of GaxIn1−xAs is disposed below the cap layer and defines a resistive layer opening in registration with the cap layer opening and having a first width. A Schottky layer of AlyIn1−yAs is disposed below the resistive layer. An undoped channel layer is disposed below the Schottky layer. A semi-insulating substrate is disposed below the channel layer. A top surface of the Schottky layer beneath the resistive layer opening provides a recess having a second width smaller than the first width. A gate electrode is in contact with a bottom surface of the recess provided by the Schottky layer.

Abstract: By using the InGaAs layer in which the In composition is graded or varied by stages for the contact resistance reducing cap layer of the recess type compound semiconductor FET as well as using the selective etching to InAs and GaAs at the time of recess etching, the recess profile can be made curvilinear without increasing the number of processes, and occurrence of the concentration of the electric field can be thereby prevented, restriction of the high breakdown voltage value due to recess profile eliminated, and high breakdown voltage achieved.

Abstract: There is provided a hetero-junction field effect transistor including a multi-layered structure comprising a buffer layer, a channel layer composed of first semiconductor containing n-type impurity therein, a schottky layer composed of a second semiconductor including a forbidden band having a greater width than a width of a forbidden band of the first semiconductor, an electron donating layer composed of a third semiconductor which includes a forbidden band having a greater width than a width of a forbidden band of the first semiconductor, and further contains n-type impurity therein, a contact layer composed of the first semiconductor or a fourth semiconductor including a forbidden band having a smaller width than a width of a forbidden band of the first semiconductor, a gate electrode formed on an exposed surface of the schottky layer in a recess formed through the electron donating layer and the contact layer, and source and drain electrodes located around the gate electrode.

Abstract: Disclosed is a semiconductor device capable of increasing the operational speed and reducing the power consumption. The semiconductor device includes an n-channel field effect transistor and a p-channel field effect transistor which are provided on a common base-substrate. A surface region, in which the n-channel field effect transistor is provided, of the base-substrate includes: a silicon substrate; a buffer layer formed on the silicon substrate, the buffer layer being made from a silicon-germanium compound having a germanium concentration gradually increased toward an upper surface of the buffer layer; a relax layer formed on the buffer layer, the relax layer being made from a silicon-germanium compound having a germanium concentration nearly equal to that of a surface portion of the buffer layer; and a silicon layer formed on the relax layer. Source/drain regions are formed in the silicon layer.

Abstract: Disclosed is an improved field effect transistor (FET) employing both a metal-semiconductor (MES) gate and a metal-insulator-semiconductor (MIS) gate, which FET is particularly useful to provide amplification at microwave frequencies. The use of the MIS gate with appropriate biasing allows the carrier density within a selected portion of the device's channel region to be controlled. The carrier density control increases the breakdown voltage of the FET and enables the FET to be operated with higher maximum channel current and a higher drain to source voltage. As a result, higher output power is provided as compared to prior art MESFET devices of a similar size. Also disclosed is an amplifier circuit including the MES/MIS FET of the preset invention, which amplifier circuit further includes means coupled to the MES/MIS FET for dividing a high frequency input signal to provide a first divided portion and a second divided portion.

Abstract: A semiconductor device includes two or more semiconductor elements provided on a semi-insulating substrate with a buffer layer and an interlevel film being interposed therebetween, an element isolating portion provided as a result of forming a groove between the two or more semiconductor elements through the buffer layer and the interlevel film so as to reach the semi-insulating substrate, and a protective film for protecting at least ends of the buffer layer in the vicinity of the element isolating portion.

Abstract: A first surface layer made of compound semiconductor material is defined in a surface area of a substrate. A first intermediate layer is formed on the surface layer, the first intermediate layer being made of compound material having Ga as a III group element and S as a VI element and having a thickness of at least two monolayers or thicker. A first electrode is formed on the first intermediate layer, being electrically connected to the first surface layer with an ohmic contact.

Abstract: A method for fabricating a periodic table group III-IV metal semiconductor metal field-effect enhancement mode complementary transistor pair device is described, a device typically made of gallium arsenide materials. The disclosed fabrication uses initially undoped semiconductor materials, single metallization for ohmic and Schottky barrier contacts, employs a non-alloyed ohmic contact semiconductor layer and includes an inorganic dielectric material layer providing non photosensitive masking at plural points in the fabrication sequence. The invention uses selective ion implantations, and a combined optical and electron beam lithographic process, the latter in small dimension gate areas. These attributes are combined to provide a field-effect transistor complementary pair of reduced fabrication cost, low electrical energy operating requirements increased dimensional accuracy and current state of the art electrical performance. Fabricated device characteristics are also disclosed.

Abstract: A laminated layer having a layer containing Al (In) and a layer not containing Al (In) alternately laminated one upon another is plasma etched by an etchant gas which can etch both the layers containing and not containing Al (In). An additive gas containing F is added to the etchant gas while a layer not containing Al (In) is etched. When the surface of the layer containing Al (In) is exposed, fluorides are formed on the surface of the layer containing Al (In) and the etching is automatically stopped. An emission peak specific to Al (In) is monitored to detect which layer is presently etched.

Abstract: To enhance a drain current voltage characteristics of a compound semiconductor field effect transistor, an n-GaAs substrate is used. After forming an n.sup.- -GaAs layer and an i-AlGaAs layer successively on the substrate, an n-type transistor is formed on these layers. Subsequently, on the rear side of the n-GaAs substrate, an ohmic electrode is formed, to connect with a drain electrode on a surface side. In the structure, when a drain current is increased, at a drain side electron also flows toward the substrate, so that the current concentration on a drain region is relaxed. Thereby, the drain current voltage characteristics can be improved.

Abstract: On a semiconductor substrate, a channel layer, an electron supply layer, a third semiconductor layer, a second etching stopper layer, a second semiconductor layer and a first etching stopper layer and a first semiconductor layer are grown in sequential order to form E-type and D-type FETs. The third semiconductor layer and the second semiconductor layer have equal layer thickness, and the second etching stopper layer and the first etching stopper layer have the equal layer thickness. Thus, Vth of the E-type and D-type FETs can be controlled at the predetermined value with high reproduction ability.

Abstract: A highly uniform, planar and high speed JHEMT-HBT MMIC is fabricated using a single growth process. A multi-layer structure including a composite emitter-channel layer, a base-gate layer and a collector layer is grown on a substrate. The composite emitter-channel layer includes a sub-emitter/channel layer that reduces the access resistance to the HBT's emitter and the JHEMT's channel, thereby improving the HBT's high frequency performance and increasing the JHEMT's current gain. The multi-layer structure is then patterned and metallized to form an HBT collector contact, planar HBT base and JHEMT gate contacts, and planar HBT emitter and JHEMT source and drain contacts.

Abstract: A heterojunction epitaxial layer, including a first semiconductor layer containing Al and having a thickness of 50 nm or less and a second semiconductor layer different in composition from the first semiconductor layer, is formed on a substrate composed of semi-insulating GaAs. A gate electrode is formed on a specified region of the top surface of the heterojunction epitaxial layer. The source/drain formation regions of the heterojunction epitaxial layer are provided with respective high-concentration N-type impurity diffusion regions, on which respective ohmic electrodes are formed.

Abstract: A multi-layer structure inserted onto an interface between a compound semiconductor region and a highly resistive material region includes an epitaxial silicon layer up to 1.5 nm thick in contact with the compound semiconductor region and an amorphous silicon layer from 1 to 10 nm thick in contact with the highly resistive material region and laminated on the epitaxial silicon layer.

Abstract: A high-breakdown-voltage semiconductor device has a first offset layer and a second offset layer the dosage of which is higher than that of the first offset layer. When the gate is in the ON state, the first offset layer functions as a resurf layer. When the gate is in the OFF state, part of the charge in the first offset layer is neutralized by a drain current flowing through an element having a low ON-resistance, however, the second offset layer functions as a resurf layer. When the drain current is ?Acm.sup.-1 !, the amount of charge of electrons is q?C!, and the drift speed of carriers is .upsilon..sub.drift ?cms.sup.-1 !, the dosage n.sub.2 of the second offset layer is given by n.sub.2 .gtoreq.I.sub.D /(q.upsilon..sub.drift)?cms.sup.-2 !.

Abstract: A GaN-type field effect transistor exhibits a large input amplitude by using a gate insulating film. A channel layer and a gate insulating film are sequentially laminated on a substrate with a buffer layer therebetween. A gate electrode is formed on the gate insulating film. A source electrode and a drain electrode are disposed at the both sides of the gate electrode and are electrically connected to the channel layer via openings. The channel layer is formed from n-type GaN. The gate insulating film is made from AlN, which exhibits excellent insulation characteristics, thus increasing the Schottky barrier and achieving a large input amplitude. If the FET is operated in the enhancement mode, it is operable in a manner similar to a Si-MOS-type FET, resulting in the formation of an inversion layer.

Abstract: An integrated circuit technology combines heterojunction bipolar transistors (HBTs), high electron mobility transistors (HEMTs) and other components along with interconnect metallization on a single substrate. In a preferred embodiment a flat substrate is patterned, using dry etching, to provide one or more mesas in locations which will eventually support HEMTs. A device stack including HEMT and HBT layers is built up over the substrate by molecular beam epitaxy, with the active HEMT devices located on the mesas within openings in the HBT layer. In this way the active HEMT is aligned with the HBT layer to planarize the finished integrated circuit.

Abstract: A tunable antenna-coupled intersubband terahertz (TACIT) detector is based on intersubband absorption in doped semiconductor quantum wells. THz-frequency radiation impinges on a coplanar antenna. The antenna couples radiation into a narrow constriction in a two dimensional electron gas (the "active region") with electric field perpendicular to the plane of the antenna. Radiation, which is at the intersubband absorption frequency, is absorbed in the active region. The resulting change in resistance through the constriction is detected. The frequency of the absorption, and hence the detection frequency, can be tuned over the 1-5 THz range by applying small voltages between a front and back gate. The efficiency with which radiation couples from the antenna into the active region can be optimized at each frequency.TACIT detectors solve a number of outstanding problems associated with Terahertz detection including:1.

Abstract: The present invention relates to RAM circuits comprising memory cells and logic circuitry wherein each of the memory cells comprise at least one Vertical MISFET device comprising a stack of several layers a source layer, a channel layer, a drain layer and a capacitor on the top of the stack of several layers of the Vertical MISFET device.

Abstract: A semiconductor device includes a heterojunction bipolar transistor and a junction gate type field effect transistor which are formed on a semiconductor base. A base region and graft base regions of the heterojunction bipolar transistor, and a channel region and source/drain regions of the junction gate type field effect transistor, are formed of a first semiconductor layer of a first conduction type. The first semiconductor layer is formed of mixed crystals of silicon-germanium which has a higher carrier mobility than silicon. An emitter region of the heterojunction bipolar transistor and a gate region of the junction gate type field effect transistor are formed of a second semiconductor layer of a second conduction type which makes a heterojunction with the first semiconductor layer.

Abstract: A channel layer made of n-type GaAs doped with Si, a hole absorption layer made of InGaAs having a valance band higher in energy level than that of GaAs, and an undoped layer made of GaAs are formed sequentially on a semi-insulating substrate made of GaAs. A gate recess region having a pair of sidewall portions each consisting of an upper sidewall composed of the undoped layer and a lower sidewall composed of the hole absorption layer is formed on the channel region. The channel region is exposed in the gate recess region. An indent having an undercut configuration is formed in the lower sidewall of the gate recess region. A gate electrode is formed to extend over a stepped portion composed of the sidewall portion of the gate recess region closer to a drain electrode.

Abstract: A field-effect transistor including a channel layer, a source electrode, a drain electrode, a high-resistance layer provided on the channel layer between the source electrode and the drain electrode and a gate electrode provided in an opening formed in the high-resistance layer, wherein the high-resistance layer is defined by a first side-wall facing the source electrode and a second side-wall facing the drain electrode, such that the first side-wall is separated from the source electrode.

Abstract: A low subthreshold leakage current, p-channel HFET including a GaAs supporting substrate with a first GaAs buffer layer and a first Al.sub.0.75 Ga.sub.0.25 As diffusion barrier layer formed thereon and a low temperature grown layer, including one of GaAs and AlGaAs, grown at 200.degree. C. on the first diffusion barrier layer. A second Al.sub.0.75 Ga.sub.0.25 As diffusion barrier layer is positioned on the low temperature grown layer and a second GaAs buffer layer is grown on the second diffusion barrier layer. A p-channel HFET is formed on the second buffer layer.

Abstract: A semiconductor quantum dot device using a semiconductor quantum dot comprises a semiconductor quantum dot formed on a semiconductor wafer, a field effect transistor formed on said semiconductor wafer and comprising a gate electrode formed in a vicinity of said semiconductor quantum dot, and a coupling means to couple said gate electrode and said semiconductor quantum dot capacitively.