Publication Details:
Journal or Publication Title:
Armenian Journal of Physics=Ֆիզիկայի հայկական հանդես
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Yerevan State University, Department of Physics
Subject:
Physics ; Electronic structure and electrical properties of surfaces ; Electronic transport in condensed matter
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Abstract:
The ground state energy and the extend of the wavefunction of a neutral donor located near a semiconductor surface in the presence of a STM metallic tip held at a fixed potential is obtained within a variational approach. We apply the effective mass approximation and use a variational wavefunction that takes into account the influence of all image charges that arise due to the presence of a metallic tip. The latter lowers the shallow donor energy which is lower than in the case when the donor is located at the same distance near a plane semiconductor-metal interface. The ionization process of a donor center due to the tip positive voltage is considered. In the case of negative voltage on the tip we observe a nonmonotonic behavior of the impurity electron binding energy.