Local p-type conductivity in zinc oxide dual-doped with nitrogen and arsenic

A doping approach for $p$ -type ZnO is reported which is reproducible and long-time stable. For $p$ -type doping the zinc oxide layers were doped simultaneously with nitrogen and arsenic in metal organic vapor phase epitaxy. The conductivity type of the layers was investigated by scanning capacitance microscopy, a technique based on local capacitance-voltage analysis $\left(C\text{-}V\right)$ with submicron spatial resolution. Depending on the growth parameters, largely extended $p$ -type domains were observed, surrounded by $n$ -type regions. The differences in local conductivity type are directly correlated to the topography as measured with atomic force microscopy revealing $p$ -type for smooth, two-dimensional surfaces and $n$ -type signals in the case of three-dimensional island growth or structural defects, i.e., microcracks or surface pits.