Improving the chemical potential of nitrogen to tune the electron density and mobility of ZnSnN2

Abstract

To meet device applications, it is essential to fabricate nondegenerate ZnSnN₂ with higher mobility. Herein, the chemical potential of nitrogen was improved under Zn-rich sputtering conditions and nondegenerate ZnSnN₂ with mobility higher than 20 cm² V⁻¹ s⁻¹ was successfully fabricated. The properties of the samples were characterized. The obtained ZnSnN₂ is wurstite. Band conduction is observed in the range 300–100 K and nearest neighbour hopping is observed in the range 100–70 K. The forbidden band gap is about 1.43 eV and Sn substituting Zn is the major donor, whose ionization energy is 34.6 meV. Improving the chemical potential of nitrogen under Zn-rich conditions effectively changes the off-stoichiometry of ZnSnN₂ and unintentionally increases oxygen doping, which finally leads to a decrease in electron density and an increase in mobility.