Hello, This is not exactly a question on QE but a general question on computing electrostatic potential near a metal-semiconductor interface using DFT. I would really appreciate thoughts from the QE community.
There exists a lot of DFT papers that plot the electrostatic potential near a metal-semiconductor interface and use it to obtain the Schottky barrier height. Here's one such example where the authors work with a RhSi (metal) - Si interface: http://scitation.aip.org/content/aip/journal/jap/112/9/10.1063/1.4761994 You will notice from Figure 3 in that paper that the average electrostatic potential (average over each sinusoidal oscillation) becomes constant in the semiconductor within a small length (~ 5 Angstrom) away from the interface. I have seen this in many other papers and in my own calculations. However, for an undoped semiconductor (no screening), the potential is not expected to become constant for at least a few tens of nm away from the interface (example: http://www.nextnano.de/nextnano3/tutorial/1Dtutorial_Schottky_barrier.htm ). I'm trying to understand why DFT predicts a very small screening length even for undoped semiconductors. I am wondering if this is a DFT limitation and thought someone might have some idea on this? I would really appreciate any thoughts. Thank you! Sridhar Purdue University
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