# Ohmic contacts

1. Mar 16, 2009

### Excom

Hallo

Is there someone that can explain why Al can be used to form Ohmic contats to both p- and n-type Si?

When looking at a Ohmic junction between a metal and a semiconductor, it is formed when the work functions are as follows: $$\Phi_m$$>$$\Phi_p$$ and $$\Phi_m$$<$$\Phi_n$$. How can Al fulfil both or is there something that I am not aware of?

2. Mar 20, 2009

### Naty1

Does this help:
Wikipedia: http://en.wikipedia.org/wiki/Ohmic_contact#Technologically_important_kinds_of_contacts

3. Mar 26, 2009

### Excom

No it does not help.

I do understand that Al can react with oxygen to form Al2O3 and thereby consum the native oxide. However, this do not explain why Al can make ohmic contact to n- and p-type silicon.