I need to create a Schottky contact on my samples of silicon to make measurements with DLTS technique, is it necessary to evaporate gold? or is there an other method which is less expensive?
As mentioned by Dr.Hajji, evaporated film of a metal will be a good option for contact for making Schottky barrier. Gold is not a prime requirement. you can choose any metal which is not making Ohmic contact with silicon but barrier height should be quite sufficient to have appreciable barrier capacitance for DLTS measurements...
The DLTS measurement generally requires depositing Schottky metal contacts on a small piece of wafer and placing it in a cryostat to measure depletion layer capacitances at cryogenic temperatures.
I think that in this case the evaporation is the simplest and easiest method.
As mentioned by Dr.Hajji, evaporated film of a metal will be a good option for contact for making Schottky barrier. Gold is not a prime requirement. you can choose any metal which is not making Ohmic contact with silicon but barrier height should be quite sufficient to have appreciable barrier capacitance for DLTS measurements...
There is no less expensive method for the Schottky barrier formation to be able to make DLTS measurements. It is most important to achieve a large barrier height so that the barrier conductance is low to be able to measure the capacitance accurately. Al is a high barrier metal on p-type silicon, while Au is a high barrier metal on n-type silicon. There are other high barrier metals, but, Au and Al are easy to evaporate.
Thermal Evaporation seems to be the best choice. Sputtering or Ebeam evaporation might cause damage in the interface between metal and semiconductor and create defects which might later mess up the DLTS results.
I agree try Al evaporation, it doesn't have to be gold for a Schottky barrier. My work was on GaAs rather than Si but evaporation is the best choice.
Thank's for all your contributions, i will try to evaporate Al.
Hi!
Au is not a good choice for making Schottky contact on Si... it diffuses very
easily inside of it, and generates deep levels both for electrons and holes... so that will affect your DLTS measurement and then you will have difficults to know if a DLTS signal comes from Au.
Personally, I use Titanium when making a Schottky contact on Silicon, both n and p-type Si, it stickes very well to the surface and also it is one of the metals that less diffuse into Si... have a look on several of my articles where I report using Ti-Si Schottky diodes, and I also report how to do them.
Remeber, FIRST make the ohmic contact, as very likely you will have to anneal it... and then make the Schottky.
Is your silicoin n- o p-type? do you know already how to make an ohmic contact on your sample?
Good luck!
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