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    Preparation of silicon carbide materials
    2.
    发明授权
    Preparation of silicon carbide materials 失效
    碳化硅材料的制备

    公开(公告)号：US3129125A

    公开(公告)日：1964-04-14

    申请号：US82419059

    申请日：1959-07-01

    Applicant: WESTINGHOUSE ELECTRIC CORP

    Inventor： HAMILTON DONALD R

    IPC: C30B23/00

    CPC classification number: C30B23/00 ,  C30B29/36 ,  Y10S117/906 ,  Y10S148/148 ,  Y10S438/919 ,  Y10S438/925 ,  Y10S438/931

    Abstract: In a method of producing a single crystal of silicon carbide containing a p-type region doped with aluminium or boron, by vaporizing a charge of SiC or the constituents thereof and the doping material and growing the crystal from the vapour, the concentration of Al or B in another region of the crystal, e.g. a transition region between p- and n-type regions, is limited by flowing a gas which is substantially free of acceptor impurity and is not significantly reactive with SiC but which is reactive with the Al or B dopant, in the vicinity of the crystal growth while the said other region is growing. Examples of such a gas are Cl, p F, and mixtures thereof with A, H, He, CO. The crystal may be grown in accordance with the methods disclosed in Specifications 772,691 and 862,600. In an example, commercially pure graphite and silicon, the latter containing 0,79% by weight of Al, are heated in a graphite crucible in argon at 2450 DEG C. for 1 1/2 hours, during which time p-type SiC crystals grow. Then 20 cc./min. each of chlorine and argon in admixture are passed down a graphite tube to the region of growth for 1 hour, after which the assembly is cooled. In other examples, nitrogen is introduced into the system, the N content being progressively increased to 5% or more while the A-Cl mixture flows; crystals grown in these conditions have inner p-type regions and outer n-type regions. Bodies of n-p-n and p-n types are obtained from the crystals by shaping. Al- or B-doped SiC or mixtures of pure Si and C to which Al or B or a compound, e.g. oxide, thereof has been added, may be used as the charge; an Al or B concentration of 0,5 to 1,5% by weight is satisfactory.

    Multicathode gate-turnoff scr with integral ballast resistors
    3.
    发明授权
    Multicathode gate-turnoff scr with integral ballast resistors 失效
    多功能门式电机与集成电阻电阻器

    公开(公告)号：US3611072A

    公开(公告)日：1971-10-05

    申请号：US3611072D

    申请日：1969-08-27

    Applicant: WESTINGHOUSE ELECTRIC CORP

    Inventor： HAMILTON DONALD R

    IPC: H01L29/08 ,  H01L29/417 ,  H01L29/74 ,  H01L29/744 ,  H01L5/02 ,  H01L9/12 ,  H01L11/10

    CPC classification number: H01L29/0839 ,  H01L29/41716 ,  H01L29/744

    Abstract: A gate controlled switch has a plurality of cathode regions distributed throughout but electrically isolated from the gate region of the switch. Each cathode region has an integral resistive portion which enables the region to control the last current flow which occurs when the switch is turned off so that each cathode region has two distinct separate regions integral with each other, and each having its own individual function. During normal operation of the switch, substantially all of the forward current flows through essentially all of the cathode except for the integral resistive portion of the region. During turnoff of the switch the last current to flow in the switch is caused to flow through the integral resistive element portion of the cathode region.

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