Question

can we use n&p-types semiconductors alternatively in several layers as dielectric?

Answer 1

I think i will never get the answers...............

Answer 2

Depends on your application.

I suppose if your application was, say, the insulation in a coaxial cable, it might work (if we ignore the fact that silicon isn't flexible). You essentially create a giant blocking diode between the two conductors. (or two blocking diodes, so current cant flow in either direction). This would work, but wouldn't perform very well for most applications. First, it would create a variable capacitance because the voltage on the conductor would change the depletion regions in the semiconductors, creating a parasitic capacitance that varies with the applied voltage. Second, depending on the thickness and doping of the semiconductor, the breakdown voltage would be a lot lower than most traditional dielectrics (SiO2, various plastics, etc).

If your application was, say, the gate insulator in a MOSFET transistor, this would NOT work at all, because the field in the gate oxide has to be constant in order to affect the conducting channel of the FET. If you were to stack n/p types the field from the gate would just accumulate carriers in the semiconductors, making a region of very high conductivity which the field lines would then terminate on.

Check out a device called a thyristor - its a stack of p/n/p/n. You might think it will never conduct current but it does, and has a very weird/cool transfer curve.