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Re: Thyristors Re: 48kW DRSSTC: international names

Original poster: FIFTYGUY@xxxxxxx In a message dated 12/5/05 2:10:39 PM Eastern Standard Time, tesla@xxxxxxxxxx writes: 

>I think thyristor is a more generalized term than SCR.

    From "SCRs and Related Thyristor Devices" (Laster, 1981):
"Further research involving semiconductor pn junctions paved the way for development of multilayer pnpn devices known as _thyristors_. The term _thyristor_ applies to a broad family of solid-state devices designed for electronic switching and control of ac and dc power.The silicon controlled rectifier (SCR), for example, is a thyristor for controlling current in a forward direction..." 

>Isn't a triac a specialized form of thyristor?
"...Other thyristors, such as the triac, can be used to switch current in either direction. As you may have concluded, the thyristor has made the older thyratron tube obsolete." 

> Things like GTO (Gate Turn Off)
>devices are also called thyristors. I suspect that there are other
>interesting devices (LASCRs, Quadracs, etc.) that fall in the thyristor category. 
> Does a thyristor have to have 4 layers?  And, would it include Triac,
> but not backtoback SCRs in the same package?

    Laster lists:

    SCR
    Triac (Bidirectional Triode Thyristor)
    Diac (Bidirectional Trigger Diode)
    SCS (Silicon Controlled Switch)
    GTO (Gate Turn-off Switch)
    LASCR (Light Activated SCR)
UJT (Unijunction Transistor) - "Invented about the same time as the bipolar junction transistor, the UJT may considered to be a member of both the transistor and thyristor families." Of course, it has just two layers. 
    PUT (Programmable UJT) - has four layers.
    Shockley Diode
    SUS (Silicon Unilateral Switch)
SBS (Silicon Bilateral Switch) - SUS and SBS are really integrated circuits to approach "ideal" SCR performance. 

> Has anyone made a Germanium 4 layer diode with a gate?  Would that be a GCR?

    LOL! Good question!
    FWIW, "Electronics Engineer's Handbook" (Fink, 1975) says:
"The energy gap of germanium, .67eV, precludes its use at temperatures higher than 80oC. Germanium cannot be conveniently fabricated by the planar technology because its oxide is not stable." 

-Phil LaBudde