Metal-semiconductor junction

[Moreno]

Let say we will bring negatively charged metal plate in contact with p-type semiconductor. Will electrons from charged plate enter p-type semiconductor and recombine with holes under condition that metal work function is much higher than that of a p-type semiconductor?

Similarly, what if we bring positively charged metal plate in contact with p-type semiconductor, under condition that metal work function is much higher than that of p-type semiconductor? Will valence band electrons from p-type semiconductor transfer to a positively charged metal?

Edited March 3, 2017 by Moreno

[studiot]

Let say we will bring negatively charged metal plate in contact with p-type semiconductor. Will electrons from charged plate enter p-type semiconductor and recombine with holes under condition that metal work function is much higher than that of a p-type semiconductor?

Similarly, what if we bring positively charged metal plate in contact with p-type semiconductor, under condition that metal work function is much higher than that of p-type semiconductor? Will valence band electrons from p-type semiconductor transfer to a positively charged metal?

 

Bringing metal into contact with anything can be tricky.

 

Apologies for important missed word, EDIT

 

Bringing charged metal into contact with anything can be tricky.

 

Why not connect a non charged metal object and then charge it?

This is how a point contact transistor was made.

 

https://en.wikipedia.org/wiki/Point-contact_transistor

Edited March 3, 2017 by studiot

[Moreno]

In MIS capacitor they have insulating layer between metal electrode and p-type semiconductor.

https://en.wikipedia.org/wiki/MIS_capacitor

 

But I guess, it would retain some capacitance even if there would be no insulating layer, under condition that metal's work function is higher than in p-type semiconductor?

Edited March 3, 2017 by Moreno

[Enthalpy]

A metal is full of electrons and holes. The effect of a pre-existing electrostatic charge is negligible. A much bigger amount of carriers flows between a metal and a semiconductor "when" the contact is established.

 

Because of dirt, making mechanically a contact between a semiconductor part and a metal mart makes nothing predictable. Such "Schottky" contacts are produced by depositing the metal under vacuum over a clean semiconductor surface.

https://en.wikipedia.org/wiki/Schottky_barrier

 

As band diagrams show electron energies but electrons are negative; conventions are tricky. You could better tell whether the metal's Fermi level is in the semiconductor's valence band, conduction band or gap.

 

Be aware that Schottky contacts use not to work as band diagram predict. They are plagued by surface states, which tend to make bad contacts even bands want ohmic contacts. So don't invest too much time here.