Untersuchung der Oberflächenzustände der Si(001)-Fläche mit der Kelvin-Methode

Reese, E.

Book/Report

FZJ-2018-02838

Untersuchung der Oberflächenzustände der Si(001)-Fläche mit der Kelvin-Methode

Reese, E. (Corresponding author)FZJ*

1988
Kernforschungsanlage Jülich, Verlag Jülich

Jülich : Kernforschungsanlage Jülich, Verlag, Berichte der Kernforschungsanlage Jülich 2177, 103 p. (1988)

Please use a persistent id in citations: http://hdl.handle.net/2128/18452

Report No.: Juel-2177

Abstract: The contact potential difference (CPD) and the surface photovoltage (SPV) were measured by the Kelvin technique on the clean and hydrogenated Si(001)-surface. The measurements of the photovoltage were carried out on a weakly n-doped (N$_{d}$ $\sim$ 10$^{13}$cm$^{-3}$) and on a weakly p-doped (N$_{a}$ $\sim$ 10$^{14}$cm$^{-3}$) sample in dependence of light intensity and temperature. In addition, measurements were made on the variation of the work funktion in the dark with temperature and doping. The surface photovoltage shows a linear correlation between the temperature and the logarithm of the light intensity. This particular dependence on temperature and light intensity allows the determination of activation energies, which can be attributed in the case of the clean surface to the distance of the Fermi-level from the conduction band at the surface in the dark. Some deviations are observed for the hydrogenated surface, which make the interpretation of the results more complicated. In this case, only tendencies can be shown. The work function in the dark is independent from doping and temperature. This result is obtained for the clean and for the hydrogenated surface as well and demonstrates with an accuracy of 10 meV for the first time that the Fermi-level is pinned at the Si(001)-surface. In order to explain these phenomena existing models must be modified concerning the distribution of occupied and unoccupied surface states: There is no gap between these states at the surface but a continuous distribution throughout the bulk bandgap must be assumed. Such adistribution of electronic surface states can be correlated to a structure of the Si(001)-surface, which shows a certain disorder and density of defects.

Contributing Institute(s):