SEMITIP, VERSION 2, Electrostatic Computations for a Probe Tip near a Semiconductor

R. M. Feenstra
Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213

This program computes the electrostatic potential resulting from a metallic probe tip near a semiconductor, as described in the preprint here, published in Phys. Rev. B 71, 125316 (2005). This program is an updated version of the prior VERSION 1, described here. Additional documentation for VERSION 2 is available in the SEMITIP V2 Technical Documentation, describing changes relative to VERSION 1. The major change in VERSION 2 relative to VERSION 1 is the added capability of including a distribution of surface states, which charge up in accordance with the Fermi-level position and thereby affect the band bending.

Some background information on the methods used in the program is contained in:

A compiled version of the code, which should run on any Windows PC, is available in the file semitip_v2.exe. Input for the executable code comes from the file FORT.9. Download these two files, into filenames "semitip_v2.exe" and "fort.9". Then, run the code just by double clicking on it. Using a text editor, the input parameters in FORT.9 can be changed to whatever values are desired. In addition to the parameter values, this file also contains comments as to the meaning of each parameter.

Output from the program is contained in the following files (output depends on the value of the output parameter IWRIT as specified in the input file FORT.9):

All of the parameters in the program can be varied using the input file FORT.9, with the exception of the array sizes (NRDIM, NVDIM, NSDIM, and NE), the specification of an auxiliary function other than a hemisphere which defines a protrusion on the end of the probe tip, the specification of a surface state density other than a uniform one. Modification of those parameters can be accomplished by changing the source code of the program. The source code is also available, in the files:

All routines are written in Fortran. The source code can be downloaded directly from the above locations, and it can be compiled and linked on any platform. Sample output from the above routines is shown in FORT.16.