Suppose I have two material having high carrier density (hole=5x1022 cm-3 and electron =5x1020 cm-3).. will this two film form good quality diode?
Or I can make a diode putting one p and n type layer with higher resistivity in between the afore mentioned device i.e with structure p+-p-n-n+??
Which one would provide better rectification theoretically??
P-N junction diode(.3v Ge,.7v Si) is good for normal use, as rectifier, would work parfactely as diode. With reverse biased voltage, if one need more accuracy, like zener effect, or to increased or reduced the withstand level of reversed biased voltage the n+-n to p-+p with accurate doping could be used.
MORE REGIONS WOULD FORM MORE BARRIER REGIONS AND YOU WOULD HAVE TO DECIDE WHAT APPLICATION YOU WANT TO USE THE DIODE
In the pn diode both the p-side and the n-side must build ohmic contact with electrode metals to electrically access the diode. This can be made by making the thickness of these regions sufficiently long such that the injected carriers recombine before reaching the the metallic contacts.
In case of short thickness diodes, one can make the ohmic contact to the metal by infinite recombination rate at these interfaces.
In order to easily make ohmic contacts on the p and n sides one dope them with heavy doping to form p+ pnn+ diode structure. This structure will have better ohmic contacts to the metal. The other important enhancement is that at the high injection both high low junctions will inject minority charges in the base region and the diode will be conductivity modulated and its resistance will decrease. In fact at high injection the diode acts as a pin diode which is the choice as a power diode.
Best wishes
Thank you @Zekry Sir,
Actually the p+ and n+ layers itself are much conducting and I am not going to put any metal contacts further.
I was thinking about formation of another junction at p-p+ and n-n+ interfaces.. will that affect the p+-p-n-n+ diode performance??
It depends which purposes u are going to use this diode. For rectification purpose wide depletion is preferable. So your doping need to be adjusted that can make better depletion width for rectification.
Multiple layers will form multiple barriers, and it depends for what application you are going to use the diode and the doping profile
Dear Arindam,
what do you to produce? additional junctions for what?
In principals you can stack as many layers as you wish using epitaxial growth with some constraints on the doping and thickness on the layers.
The other thing is that the heavily doped semicondcutor layers can not substitute the metal layers for electrically accessing the devices.
Best wishes
https://www.quora.com/Is-there-any-difference-between-PN-and-NP-diode
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