P-type conductivity in GaN:Zn monocrystals grown by ammonothermal method

Abstract

Zinc is often regarded as an alternative to magnesium p-type dopants in gallium nitride. However, besides many theoretical predictions, at present, there are poor data on experimentally revealed p-type conductivity and evaluation of Zn activation energy by means of electrical transport measurements. In this paper, ammonothermal crystallization of bulk GaN:Zn monocrystals is reported. Despite a high doping level of Zn (up to 2 × 1020 cm-3), p-type conductivity with hole concentration as low as of 4 × 1015 cm-3 at room temperature and mobility about 3 cm2/V s was observed. A deep nature of the Zn acceptor was proved, as the ionization energy can exceed 260 meV. In addition, conduction in the impurity band appeared at temperatures as high as room temperature.