Abstract: A reflector assembly for a molten chloride fast reactor (MCFR) includes a support structure with a substantially cylindrical base plate, a substantially cylindrical top plate, and a plurality of circumferentially spaced ribs extending between the base plate and the top plate. The support structure is configured to encapsulate a reactor core for containing nuclear fuel. The MCFR also includes a plurality of tube members disposed within the support structure and extending axially between the top plate and the bottom plate. The plurality of tube members are configured to hold at least one reflector material to reflect fission born neutrons back to a center of the reactor core.

Abstract: This disclosure describes various configurations and components of a molten fuel fast or thermal nuclear reactor for managing the operating temperature in the reactor core. The disclosure includes various configurations of direct reactor auxiliary cooling system (DRACS) heat exchangers and primary heat exchangers as well as descriptions of improved flow paths for nuclear fuel, primary coolant and DRACS coolant through the reactor components.

Abstract: Configurations of molten fuel salt reactors are described that utilize neutron-reflecting coolants or a combination of primary salt coolants and secondary neutron-reflecting coolants. Further configurations are described that circulate liquid neutron-reflecting material around a reactor core to control the neutronics of the reactor. Furthermore, configurations which use the circulating neutron-reflecting material to actively cool the containment vessel are also described.

Abstract: Configurations of molten fuel salt reactors are described that allow for active cooling of the containment vessel of the reactor by the primary coolant. Furthermore, naturally circulating reactor configurations are described in which the reactor cores are substantially frustum-shaped so that the thermal center of the reactor core is below the outlet of the primary heat exchangers. Heat exchanger configurations are described in which welded components are distanced from the reactor core to reduce the damage caused by neutron flux from the reactor. Radial loop reactor configurations are also described.

Abstract: Configurations of molten fuel salt reactors are described that include an auxiliary cooling system which shared part of the primary coolant loop but allows for passive cooling of decay heat from the reactor. Furthermore, different pump configurations for circulating molten fuel through the reactor core and one or more in vessel heat exchangers are described.

Abstract: Configurations of molten fuel salt reactors are described that utilize neutron-reflecting coolants or a combination of primary salt coolants and secondary neutron-reflecting coolants. Further configurations are described that circulate liquid neutron-reflecting material around an reactor core to control the neutronics of the reactor. Furthermore, configurations which use the circulating neutron-reflecting material to actively cool the containment vessel are also described.

Abstract: A dynamic neutron reflector assembly for a “breed-and-burn” fast reactor incrementally adjusts neutron spectrum and reactivity in a reactor core. The composition of materials in the dynamic neutron reflector may be adjusted to change neutron reflectivity levels, or to introduce neutron moderating or absorption characteristics. The dynamic neutron reflector may contain a flowing reflecting liquid of adjustable volume and/or density. Submergible members may be selectively inserted into the flowing reflecting liquid to alter its volume and introduce other neutron modifying effects such as moderation or absorption. Selective insertion of the submergible members allows for concentration of the neutron modifying effects in a selected portion of the reactor core. The flowing reflecting liquid may also act as a secondary coolant circuit by exchanging heat with the molten fuel salt.

Abstract: Disclosed is a method of forming a semiconductor structure that includes a discontinuous non-planar sub-collector having a different polarity than the underlying substrate. In addition, this structure includes an active area (collector) above the sub-collector, a base above the active area, and an emitter above the base. The distance between the discontinuous portions of the discontinuous sub-collector tunes the performance characteristics of the semiconductor structure. The performance characteristics that are tunable include breakdown voltage, unity current gain cutoff frequency, unity power gain cutoff frequency, transit frequency, current density, capacitance range, noise injection, minority carrier injection and trigger and holding voltage.

Abstract: The mobility of charge carriers in a bipolar (BJT) device is increased by creating compressive strain in the device to increase mobility of electrons in the device, and creating tensile strain in the device to increase mobility of holes in the device. The compressive and tensile strain are created by applying a stress film adjacent an emitter structure of the device and atop a base film of the device. In this manner, the compressive and tensile strain are located in close proximity to an intrinsic portion of the device. A suitable material for the stress film is nitride. The emitter structure may be “T-shaped”, having a lateral portion atop an upright portion, a bottom of the upright portion forms a contact to the base film, and the lateral portion overhangs the base film.

Abstract: A bipolar transistor has a collector that is contacted directly beneath a base-collector junction by metallization to reduce collector resistance. A conventional reach-through and buried layer, as well as their associated resistance, are eliminated. The transistor is well isolated, nearly eliminating well-to-substrate capacitance and device-to-device leakage current. The structure provides for improved electrical performance, including improved fT, Fmax and drive current.

Abstract: A structure and method where C is incorporated into the collector region of a heterojunction bipolar device by a method which does not include C ion implantation are provided. In the present invention, C is incorporated into the collector by epitaxy in a perimeter trench etched into the collector region to better control the carbon profile and location. The trench is formed by etching the collector region using the trench isolation regions and a patterned layer over the center part of the collector as masks. Then, Si:C is grown using selective epitaxy inside the trench to form a Si:C region with sharp and well-defined edges. The depth, width and C content can be optimized to control and tailor the collector implant diffusion and to reduce the perimeter component of parasitic CCB.

Abstract: A field effect transistor is provided which includes a contiguous single-crystal semiconductor region in which a source region, a channel region and a drain region are disposed. The channel region has an edge in common with the source region as a source edge, and the channel region further has an edge in common with the drain region as a drain edge. A gate conductor overlies the channel region. The field effect transistor further includes a structure which applies a stress at a first magnitude to only one of the source edge and the drain edge while applying the stress at no greater than a second magnitude to another one of the source edge and the drain edge, wherein the second magnitude has a value ranging from zero to about half the first magnitude. In a particular embodiment, the stress is applied at the first magnitude to the source edge while the zero or lower magnitude stress is applied to the drain edge.

Abstract: Methods of boosting the performance of bipolar transistor, especially SiGe heterojunction bipolar transistors, is provided together with the structure that is formed by the inventive methods. The methods include providing a species-rich dopant region comprising C, a noble gas, or mixtures thereof into at least a collector. The species-rich dopant region forms a perimeter or donut-shaped dopant region around a center portion of the collector. A first conductivity type dopant is then implanted into the center portion of the collector to form a first conductivity type dopant region that is laterally constrained, i.e., confined, by the outer species-rich dopant region.

Abstract: A structure and method where C is incorporated into the collector region of a heterojunction bipolar device by a method which does not include C ion implantation are provided. In the present invention, C is incorporated into the collector by epitaxy in a perimeter trench etched into the collector region to better control the carbon profile and location. The trench is formed by etching the collector region using the trench isolation regions and a patterned layer over the center part of the collector as masks. Then, Si:C is grown using selective epitaxy inside the trench to form a Si:C region with sharp and well-defined edges. The depth, width and C content can be optimized to control and tailor the collector implant diffusion and to reduce the perimeter component of parasitic CCB.

Abstract: A method of increasing mobility of charge carriers in a bipolar device comprises the steps of: creating compressive strain in the device to increase mobility of holes in an intrinsic base of the device; and creating tensile strain in the device to increase mobility of electrons in the intrinsic base of the device. The compressive and tensile strains are created by forming a stress layer in close proximity to the intrinsic base of the device. The stress layer is at least partially embedded in a base layer of the device, adjacent an emitter structure of the device. The stress layer has different lattice constant than the intrinsic base. Method and apparatus are described.

Abstract: The mobility of charge carriers in a bipolar (BJT) device is increased by creating compressive strain in the device to increase mobility of electrons in the device, and creating tensile strain in the device to increase mobility of holes in the device. The compressive and tensile strain are created by applying a stress film adjacent an emitter structure of the device and atop a base film of the device. In this manner, the compressive and tensile strain are located in close proximity to an intrinsic portion of the device. A suitable material for the stress film is nitride. The emitter structure may be “T-shaped”, having a lateral portion atop an upright portion, a bottom of the upright portion forms a contact to the base film, and the lateral portion overhangs the base film.

Abstract: A bipolar transistor has a collector that is contacted directly beneath a base-collector junction by metallization to reduce collector resistance. A conventional reach-through and buried layer, as well as their associated resistance, are eliminated. The transistor is well isolated, nearly eliminating well-to-substrate capacitance and device-to-device leakage current. The structure provides for improved electrical performance, including improved fT, Fmax and drive current.

Abstract: The present invention provides a bipolar transistor having a raised extrinsic base silicide and an emitter contact border that are self-aligned. The bipolar transistor of the present invention exhibit reduced parasitics as compared with bipolar transistors that do not include a self-aligned silicide and a self-aligned emitter contact border. The present invention also is related to methods of fabricating the inventive bipolar transistor structure. In the methods of the present invention, a block emitter polysilicon region replaces a conventional T-shaped emitter polysilicon.

Abstract: Structure and a method are provided for making a bipolar transistor, the bipolar transistor including a collector, an intrinsic base overlying the collector, an emitter overlying the intrinsic base, and an extrinsic base spaced from the emitter by a gap, the gap including at least one of an air gap and a vacuum void.

Abstract: Structure and a method are provided for making a bipolar transistor, the bipolar transistor including a collector, an intrinsic base overlying the collector, an emitter overlying the intrinsic base, and an extrinsic base spaced from the emitter by a gap, the gap including at least one of an air gap and a vacuum void.