# How to check the ohmic contact to the film?

I have a thin semiconductor film deposited on an isolating substrate. I would like to check different metals to find out do they form the ohmic contact or Schottky barrier.

What is the best way to do that?

I know that ohmic contacts show a linear I-V curve. But how to measure it? Should I deposit small dots of different metal on top of the film and measure the I-V curve? How large should be the dots? And what distance between them?

Or should I deposit my semiconductor film on a conductive substrate and measure the I-V through the film?

In most of the papers people just write – we measured the I-V curve of this film and such metal, but what design do they use?

• Does your advisor have any knowledge in this area? My initial "gut" design would be to deposit a small dot (assuming you can do so without damaging the semiconductor film and avoiding any oxidized layer), but I've only done this in a factory setting (diode & transistor fab, where metallized layers are put down w/ big fancy machines). – Carl Witthoft Aug 12 '14 at 11:38
• @CarlWitthoft If advisor knew the answer, I wouldn't ask. I have access to the e-beam machine, so the process is not a problem. The problem is I don't know the design to use and between what points to measure the I-V curve. You say "deposit a small dot". Just one? Where to make the second contact? – user57136 Aug 12 '14 at 11:43
• My first hunch would be, that the proper way to measure this is with at least four contacts, because you also need to eliminate the resistivity of the film from your measurement. The most simple geometry is dots A, B, C, D in a linear arrangement. A and B are close together, so are C and D. A and D are the two dots which you use to inject the current, B and C are used to measure the potential on the film. You can improve on this with concentric electrodes or a "parallel plate" geometry. – CuriousOne Aug 12 '14 at 19:38

## 1 Answer

try to use LTM method to measure ohmic contact between metal and semiconductor?

• Could you include more information? – Sean Mar 2 '15 at 17:50
• This really isn't informative. What is the LTM method? What is it you've shown there? – Kyle Kanos Mar 2 '15 at 18:47