All Silicon transistors appear to have a reverse base emitter breakdown voltage rating of no more than about 8 VDC .It would be extremely useful to have a much higher volt rating . Some OLD germanium transistors are a bit better like say 12V but probably not worth the hassle.WHY don't they make SI transistors with a higher VEB ?

  • \$\begingroup\$ Probably because there are other ways of solving the problem. What problem are you trying to solve with high reverse breakdown anyway? \$\endgroup\$ – Brian Drummond Aug 27 '15 at 11:00
  • \$\begingroup\$ A high reverse breakbown would allow synchronous rectification at high volts where mosfets get expensive as current goes up. \$\endgroup\$ – Autistic Aug 31 '15 at 22:18
  • \$\begingroup\$ No it wouldn't. Unless there is a suitable LV supply available, the power from base drive for a bipolar synchronous rectifier would be greater than the sync. rectifier saves. High BVEBO has no influence on a the suitability of a device for this function. \$\endgroup\$ – jp314 Dec 6 '15 at 4:20

It's 'Silicon', not 'Silicone'

Most transistors are constructed to have high beta and low emitter resistance. This leads to doping the emitter as heavily as is practical, and this in turn leads to a B-E junction with a maximum voltage capability of around 5 V. Note that sometimes the BV is higher than this, but in some devices, sustained bias at E-B voltages over 5 V will cause severe degradation in the device characteristics.

  • \$\begingroup\$ jp314 you genius ! what I can infer from your valid answer is that if such a device was made then it would have crappy gain ? If I could live with a gain of less than one then is such a device theoraticly possible ? \$\endgroup\$ – Autistic Dec 6 '15 at 4:23
  • \$\begingroup\$ Synch rectifier just to make things easy for others to understand .Not the target app. \$\endgroup\$ – Autistic Dec 6 '15 at 4:26
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    \$\begingroup\$ Sure they are possible. In Integrated circuits when PNPs are available, they generally have BVCEO = BVEBO, and this can be as high as 40 V. Those device are not generally available individually (and would be very expensive). I think there were some discrete PNPs available with high BVEBO, but I can't find them online now. \$\endgroup\$ – jp314 Dec 6 '15 at 4:28
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    \$\begingroup\$ Sure -- if you don't want high gain, choose a low BVCEO device, and operate in reverse ! You will get high 'BVEBO', but low 'BVCEO' (with emitter & collector swapped). A low (forward) BVCEO device will have higher reverse gain than a high voltage device. \$\endgroup\$ – jp314 Dec 6 '15 at 4:31
  • \$\begingroup\$ So I could use a HVBJT as a diode in CB mode and use the emitter as the collector and not worry about less than unity gain and make sure Ib is not exceeded. \$\endgroup\$ – Autistic Dec 30 '15 at 8:23

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