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Register a new userScreening and impurity ionization energy in semiconductors
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Authors
Yuri Kornyushin
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Usually microscopic electrostatic field around charged impurity ions is neglected when the ionization energy is concerned. The ionization energy is considered to be equal to that of a lonely impurity atom. Here the energy of the electrostatic field around charged impurity ions in semiconductor is taken into account. It is shown that the energy of this field contributes to decrease in the effective ionization energy. At high enough current carriers concentration the effective ionization energy becomes zero.
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Determination of defect ionization energy in low-dimensional semiconductors has been a long-standing unsolved problem in first-principles defect calculations because the commonly used methods based on jellium model introduce an unphysical charge density uniformly distributed in the material and vacuum regions, causing the well-known divergence issue of charged defect formation energies. Here in this work, by considering the physical process of defect ionization, we propose a charge correction method based on jellium model to replace the unphysical jellium background charge density with the band edge charge density to deal with charged defects. We demonstrate that, our method is physically meaningful, quantitatively accurate and technically simple to determine the defect ionization energies, thus solving the long-standing problem in defect calculations. Our proposed method can be applied to any dimensional semiconductors.
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