Whenever we do the electrical conduction there may be a development of Schottky barrier between the contacts. I am struck with the measurement of the Barrier potential. How one could remove or measure this?
Existence of SB's depends to two things: 1) conductivity type of semiconductor (p-n type), 2) work functions of two materials. If we assign Xs and Xm as work functions of semiconductor and metal respectively, then, there are four possibilities:
1) n-type semiconductor and Xs Xm, Ohmic (no barrier)
3) p-type semiconductor and Xs < Xm, Ohmic
4) p-type semiconductor and Xs > Xm, Schottky
If you want to get free from blocking contacts, you must select proper metals.
If you have blocking contacts, to measure or determine the barrier height you can follow the standart procedure presented in the attached figure. Here, IS is value of current for V=0, A diode area, A* Richardson coefficient which is not a mere constant and other well-known symbols...
There are other methods, i.e. CV measurement, to determine SB height, but IV, probably, is the simplest one.
Existence of SB's depends to two things: 1) conductivity type of semiconductor (p-n type), 2) work functions of two materials. If we assign Xs and Xm as work functions of semiconductor and metal respectively, then, there are four possibilities:
1) n-type semiconductor and Xs Xm, Ohmic (no barrier)
3) p-type semiconductor and Xs < Xm, Ohmic
4) p-type semiconductor and Xs > Xm, Schottky
If you want to get free from blocking contacts, you must select proper metals.
If you have blocking contacts, to measure or determine the barrier height you can follow the standart procedure presented in the attached figure. Here, IS is value of current for V=0, A diode area, A* Richardson coefficient which is not a mere constant and other well-known symbols...
There are other methods, i.e. CV measurement, to determine SB height, but IV, probably, is the simplest one.
If you need it for experimental purpose, then, sputter deposit chromium layer (~100 nm) and sputter deposit gold layer (~350 nm) on top of chromium layer.
Basically, you will need to make four pad Chromium/gold, on top of you semiconductor, then attach Cu wires on top of the pads using Ag paint.
Your Ohmic contacts are ready!!
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