Abstract: An amalgam is accurately placed and retained in an optimal location near the cold spot of an electrodeless SEF lamp for operation at a mercury vapor pressure in the optimum range from approximately four to seven millitorr. The amalgam is positioned at the tip of an extended exhaust tube near the apex of the lamp envelope by forming an indentation in the exhaust tube and, in some embodiments, a dose locating member in combination therewith. An evacuation hole is formed below the indentation for evacuation of the lamp envelope, or bulb, during lamp fabrication. In an alternative embodiment, the extension of the exhaust tube is situated perpendicular to the main portion of the tube to allow for lateral adjustment of the position of the amalgam, thereby allowing for even further control of the amalgam operating temperature.

Abstract: An electrodeless SEF fluorescent discharge lamp of the type having an envelope with a re-entrant cavity formed therein for containing an excitation coil includes an amalgam positioned for maintaining an optimum mercury vapor pressure during lamp operation. The amalgam is doped with a magnetic material, such as iron, cobalt, nickel, aluminum or tungsten, and is initially located in an optimal operating position using a magnetic field generated by a magnet situated about the lamp envelope. Advantageously, the magnetic field can be used to relocate the amalgam within the exhaust tube, as desired, during lamp processing steps. After processing, the magnet is removed, and no amalgam holder is required.

Abstract: A high intensity discharge lamp having a fill including at least one rare earth metal iodide has an additional metal component for avoiding a substantial loss of the metal component of the fill and the attendant substantial buildup of free iodine, thereby increasing the useful life of the lamp. During lamp operation, the additional metal component combines with iodine in the vapor phase, forming a relatively stable iodide and thus reducing the total level of free iodine in the lamp. As a result, arc instability is avoided. The additional metal component also emits visible light and hence improves efficacy. Moreover, the additional metal component does not attack the arc tube wall by reducing silica. Suitable additional metal components include indium and thallium.

Abstract: A coating for the arc tube of a high intensity metal halide discharge lamp includes at least two oxide layers for protecting the arc tube from devitrification, cracking and etching of the arc tube wall and for avoiding arc instability, thereby extending the useful life of the lamp. A first layer of the multi-layer oxide coating is applied directly to the arc tube to provide thermal compatibility in order to avoid cracking during lamp operation. At least one additional layer provides chemical stability of the arc tube wall with respect to the lamp fill. As a result, a substantial loss of the metal portion of the fill and a corresponding substantial buildup of free halogen are avoided, thereby avoiding devitrification and etching of the arc tube wall. Furthermore, for HID lamps including as a fill ingredient a metal, such as sodium, which diffuses into the arc tube wall and causes further devitrification thereof, at least one layer of the multi-layer oxide coating acts as metal-barrier.

Abstract: In-situ extraction of contaminants, such as PCBs, from soil is achieved by an electroosmosis technique. The soil is treated with a low concentration surfactant solution used as a purging liquid. The contaminant is dissolved in the ground water, aided by the purging liquid. An electric field is applied to a region of the soil causing the ground water, contaminant and surfactant to move by electroosmosis to a collection point where the purging liquid, dissolved contaminant and surfactant are collected and removed from the soil. This method may also be used to control the direction of seepage of the contaminants.

Abstract: A semiconductor power switching device comprises a multicellular FET structure with a Schottky barrier diode structure interspersed therewith with at least some of the FET cells being free of Schottky barrier portions. The ratio of Schottky barrier contact area to FET cell area in the overall device may be adjusted to tailor the device for operation at specific current densities.

Abstract: A field controlled diode is provided with an insulated gate electrode for controlling the conductivity of the diode. The diode is turned off by applying a gate bias voltage which pinches off the drift region of the device to block current flow in the anode/cathode diode path. The turn-off characteristics of the device are enhanced by including transistor portions in the structure in which the drift region is not pinched off during turn-off to facilitate extraction of stored charge from the diode structure.

Abstract: A UMOS IGBT has a source electrode ohmic contact area which is at least 40% base region and preferably at least 50% base region in order to provide a high latching current and a large safe operating area.

Abstract: Improved trench gate field effect devices are provided by forming a thick oxide at the bottom of the trench. This thick oxide may be preferably formed by ion implantation into the bottom of the trench.

Abstract: A semiconductor power rectifier attains low forward voltage drop, low reverse leakage current and improved switching speed by utilizing Schottky contact regions in a p-i-n rectifier along with other means for reducing the required forward bias voltage. In a preferred embodiment, the other means for reducing the required forward bias voltage includes a respective trench between each respective pair of successively spaced current interruption means.

Abstract: A depletion mode thyristor includes a plurality of regenerative segments and a plurality of non-regenerative segments, each of which is elongated in a first direction. Regenerative and non-regenerative segments are interleaved in a second direction perpendicular to said first direction. A plurality of regenerative segments may be disposed between adjacent non-regenerative segments. Adjacent regenerative or non-regenerative segments are spaced apart by gate electrode segments which are effective, upon application of an appropriate bias voltage, for pinching off the regenerative segments to force the current therein to transfer to the non-regenerative segments to turn the device off. This structure enables large quantities of current to be transferred from regenerative segments to non-regenerative segments during turn-off without inducing detrimental current crowding.

Abstract: An insulated field effect semiconductor device having source and drain regions extending to opposed surfaces of its semiconductor body is bidirectional and capable of blocking voltages in either of two opposing polarities and comprises a four terminal device having source and drain electrodes disposed on the opposed surfaces and a base electrode all ohmically connected to corresponding portions of the semiconductor body. An insulated gate is provided in a trench which extends into the semiconductor body for controlling the conductivity of a channel region extending within the base region between the source and drain regions. The device is free of source-to-base and drain-to-base short circuits. Control circuits enable this device to conduct or block both polarities of a high current AC voltage applied across its source and drain terminals while preventing undesired avalanche breakdown within the device.

Abstract: A lateral depletion mode thyristor has both of its power electrodes and both of its emitter regions extending to the same surface of the semiconductor wafer. The device operates with both a regenerative current path and a non-regenerative current path. An insulated gate electrode structure is disposed in a trench and configured to pinch off the regenerative current path to force the current flowing therein to transfer to the non-regenerative current path, thereby interrupting the regenerative action within the device and causing it to turn off. In some embodiments, a second insulated gate electrode controls device turn-on.

Abstract: A synchronous rectifier is able to operate at higher frequencies and provides an output having lower noise than prior art FET synchronous rectifier system by using field effect switching devices which contain only one conductivity type of semiconductor material and connecting a high speed, low charge storage diode in parallel. Schottky diodes are preferred whereby there is no junction diode in the structure. Conventional FETs may be used when paralleled with a Schottky diode which prevents the FET's parasitic internal diode from becoming conductive.

Abstract: A power field effect device has a high voltage blocking junction which intersects the device surface under the gate electrode. That intersection is a closed plane geometric figure whose center is within the body region of the device rather than in the more heavily doped base region of the device. The figure preferably is everywhere convex and has a maximum width of substantially less than the depletion width, at breakdown, of a corresponding parallel plane junction. The device breakdown voltage is higher than the breakdown voltage of a corresponding junction having a cylindrical edge with a straight axis. In a preferred embodiment, the high voltage blocking junction has a plurality of such intersections with the device surface, each situated beneath a segment of the gate electrode. In a bipolar embodiment, the gate electrode may be omitted.

Abstract: A power field effect device has a gate grid having a plurality of elongate openings therein through which a base region forming a high voltage blocking junction with the underlying body was diffused. The openings have round ends in order to prevent the formation of spherical portions in the high voltage blocking junction. The round ends of adjacent openings are positioned close enough to each other that their diffusion regions merge, thereby raising the device breakdown voltage to that of the cylindrical junction portion along the straight edges of the junction. In an alternative embodiment, the openings do not have round ends and are positioned close enough together that their diffusions merge end to end.