Article

Doping by Large-Size-Mismatched Impurities: The Microscopic Origin of Arsenic- or Antimony-Doped p -Type Zinc Oxide

Pusan National University, Busan, Busan, South Korea
Physical Review Letters (Impact Factor: 7.51). 05/2004; 92(15):155504. DOI: 10.1103/PhysRevLett.92.155504
Source: PubMed

ABSTRACT

Based on first-principles calculations, a model for large-size-mismatched group-V dopants in ZnO is proposed. The dopants do not occupy the O sites as is widely perceived, but rather the Zn sites: each forms a complex with two spontaneously induced Zn vacancies in a process that involves fivefold As coordination. Moreover, an As(Zn)-2V(Zn) complex may have lower formation energy than any of the parent defects. Our model agrees with the recent observations that both As and Sb have low acceptor-ionization energies and that to obtain p-type ZnO requires O-rich growth or annealing conditions.

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    • "A model has been proposed for group-V dopants, such as As and Sb, to achieve reliable p-type conduction in ZnO (Limpijumnong et al., 2004). In this model, a Sb Zn -2V Zn complex was considered to primarily cause the acceptor-like behavior in the Sb-doped ZnO (SZO) films (Limpijumnong et al., 2004). According to their theory, the Sb atom occupying Zn side (Sb Zn ) in ZnO has sufficient energy to spontaneously induce two zinc vacancies (V Zn ), forming a shallow acceptor complex (Sb Zn - 2V Zn ) with a formation energy ( H f ) of 2.0 eV and an acceptor ionization energy of 0.16 eV. "

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    • "who suggested that annealing at high temperature in O-rich atmosphere may result in breaking of the As–O bonds and formation of As Zn –2V Zn acceptor-like complexes [16] [18]. "
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    • "It is seen that the monodoped film (AlN ¼ 0%) showed p-conductivity with the hole concentration , $ 10 15 cm À 3 due to the diffusion of As atoms into ZnO. Here, the As sits on Zn site and thereby forms (As Zn À 2V Zn ) complexes which gives rise to p-conductivity [10]. Further, the hole concentration increases with the increase of AlN concentration (till 1 mol%) due to the incorporation of both N and As acceptors into ZnO. "
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