Posted by Roger Brennan (66.122.81.186) on January 12, 2011 at 17:41:53:
In Reply to: Re: SIMS VS. SRP posted by Yue Zu on January 11, 2011 at 13:23:38:
SRP doesn't have a special treatment for the depletion region and as a consequence reports the carrier concentration too high and the resistivity too low. Within the depletion region, the carrier concentration should be approaching zero and the resistivity should be approaching infinity.
I don't know how TCAD works but my first thought would be to attempt curve-fitting using the data outside the depletion region. If a Gaussian, error function, or straight line fits the data, this should be fairly straight forward. BEWARE!! Phosphorus >5e19cm-3 does not fit an easily used function (but TCAD may have already solved the problem). Fair and Tsai have written extensively on this subject. Please give me a call if you like.
: : : How can i get the atomic concentration (atoms/cm^3) from SRP profile?
: : In single crystal, (i.e. good carrier mobility), SRP calculates a value equal to the net electrically active atomic concentration exclusive of space-charge (depletion) regions. To put it another way, there is often nearly a 1:1 ratio between carrier concentration and atomic (dopant) concentration. Exceptions are electrical junctions, poly, unannealed implants, and VERY high dopant concentrations. One thought to keep in mind is the carrier concentration (SRP) almost exclusively controls the device performance.
: You said depletion region is the exception of 1:1 ratio of dopant concentration and carrier concentration. My questions is then how the dopant concentration is calculated and reported by SRP at the depletion region. Is there a different formular used to compensate for the depletion effect? We are feeding the SRP profile into TCAD simulation. By doing that, are we letting the already depleted profile to deplete again?