Department of Physics, Centre for Material Science and Nanotechnology, University of Oslo, P.O. Box 1048, Blindern, N-0316 Oslo, Norway.
Phys Rev Lett. 2013 Apr 26;110(17):175503. doi: 10.1103/PhysRevLett.110.175503.
Sublattice localization of impurities in compound semiconductors, e.g., ZnO, determines their electronic and optical action. Despite that the impurity position may be envisaged based on charge considerations, the actual localization is often unknown, limiting our understanding of the incorporation and possible doping mechanisms. In this study, we demonstrate that the preferential sublattice occupation for a number of impurities in ZnO can be revealed by monitoring Li diffusion. In particular, using ion implantation, the impurity incorporation into the Zn sublattice (holds for, B, Mg, P, Ag, Cd, and Sb) manifests in the formation of Li-depleted regions behind the implanted one, while Li pileups in the region of the implantation peaks for impurities residing on O sites, e.g., N. The behavior appears to be of general validity and the phenomena are explained in terms of the apparent surplus of Zn and O interstitials, related to the lattice localization of the impurities. Furthermore, Cd+O and Mg+O co-doping experiments revealed that implanted O atoms act as an efficient blocking "filter" for fast diffusing Zn interstitials.
杂质在化合物半导体中的亚晶格定位，例如 ZnO，决定了它们的电子和光学行为。尽管可以根据电荷考虑来设想杂质的位置，但实际的定位通常是未知的，这限制了我们对掺入和可能的掺杂机制的理解。在这项研究中，我们证明了通过监测 Li 扩散可以揭示 ZnO 中许多杂质的优先亚晶格占据。具体来说，使用离子注入，杂质掺入 Zn 亚晶格（适用于 B、Mg、P、Ag、Cd 和 Sb）会在注入区后形成 Li 耗尽区，而对于位于 O 位的杂质，如 N，Li 堆积在注入峰区。这种行为似乎具有普遍的有效性，并且可以根据与杂质的晶格定位相关的 Zn 和 O 间隙原子的明显过剩来解释这些现象。此外，Cd+O 和 Mg+O 共掺杂实验表明，注入的 O 原子充当快速扩散 Zn 间隙原子的有效阻挡“过滤器”。
