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

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.