Origin of n- and p-type conductivity in undoped $\alpha$-PbO: role of defects
| Autor: | Berashevich, J., Rowlands, J. A., Reznik, A. |
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| Rok vydání: | 2013 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1088/0953-8984/25/47/475801 |
| Popis: | The first principles calculations (GGA) have been applied to study the crystallographic defects in $\alpha$-PbO in order to understand an origin of $n$- and $p$-type conductivity in otherwise undoped $\alpha$-PbO. It was found that deposition in the oxygen-deficient environment to be defined in our simulations by the Pb-rich/O-poor limit stimulates a formation of the O vacancies and the Pb interstitials both to be characterized by quite low formation energies $\sim$ 1.0 eV. The O vacancy being occupied by two electrons shifts a balance of electrons and holes between these two defects to excess of electrons (four electrons against two holes) that causes the $n$-type doping. For the Pb-poor/O-rich limit, an excess of oxygen triggers a formation of the O interstitials characterized by such a low formation energy that spontaneous appearance of this defect is predicted. It is shown that the concentration of the O interstitials is able to reach the extreme magnitude equal to number of the possible defect sites ($\sim 10^{22}$cm$^{-3}$). The localized state formed by the O interstitial is occupied by two holes and because there are no other defects in reasonable concentration to balance the hole redundancy, $p$-type doping is induced. Comment: 5 pages, 3 figures |
| Databáze: | arXiv |
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