SEMITIP V6, program Uni2


This program computes the electrostatic potential between a metallic tip and a uniform (homogeneous) semiconducting sample, for a 3-dimensional geometry with azimuthal symmetry.

Version information

Version 6.6; see top of Uni2-6.6.f source code for prior version information.


A compiled version of the code, which should run on any Windows PC, is available in the file Uni2.exe. Input for the executable code comes from the file FORT.9. Download these two files, into filenames "Uni2.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. See SEMITIP V6 Technical Manual for additional comments on the meaning of the parameters.


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, the specification of a surface state density other than a uniform or Gaussian shaped one, and the specification of spatial arrangement of bulk or surface charge density. See SEMITIP V6 Technical Manual for additional information on these user-defined functions. Modification of those functions can be accomplished by changing the source code of the program. The source code is available, in the following files (version numbers follow the dash in the names):

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 input and output from the program is shown in the examples below.

Illustrative Examples of Running the Code

  1. n-type GaAs(110)
  2. n-type GaAs(110), with extrinsic surface states
  3. n-type GaAs(110), with hemispherical protrusion on end of probe tip
  4. undoped semiconductor, with no surface states
  5. comparison with inverse solution, for undoped semiconductor
  6. undoped GaAs(110), with on-center point charge