Theory and experimental measurement of work function for electrons in doped silicon surfaces are presented in the article. Definitions of work function and of the local work function are given in the introduction. It was shown, that the value of work function defines the position of Fermi energy level. Numerical calculations of surface potential and electric field for theoretical semiconductor surface models show the difference between finite and infinite surfaces. Photovoltage dependence on charge carriers injection ratio for doped silicon surface was numerically calculated as well. Experimentally determined Fermi energies of doped silicon samples show good agreement with theory for low and moderately doped samples only. Appropriate explanations of disagreement between theory and experiment are given in the conclusion. Suggestions for the system improvement are presented in the Appendix. (C) 2009 Elsevier Ltd. All rights reserved.