The activation energy of the nitrogen acceptor in p-type ZnO film grown by plasma-assisted molecular beam epitaxy

The nitrogen-doped, p-type ZnO film was grown by plasma-assisted molecular beam epitaxy (P-MBE) on cc-plane sapphire (c-Al2O3) using radical NO as oxygen and nitrogen sources. The activation energy of the nitrogen acceptor (AENA) was obtained by the temperature-dependent Hall effect and photoluminescence (PL) measurements, respectively. However, the values of AENA were rather different for the two methods, i.e., 75 meV for the Hall effect measurement and 145 meV for the photoluminescence measurement. In terms of the electrostatic interaction model, this energy difference was explained by the relationship between the Hall activation energy and the optical activation energy. According to these analyses, the reasonable value of the acceptor activation energy in nitrogen-doped p-type ZnO can be determined either by Hall experiments or by optical methods.