Synthesis of N-deficient GaN and its enhanced dielectric responses

The GaN powders were synthesized by the reaction of Ga₂O₃ and Li₃N and scanning transmission electron microscopy (STEM) analysis showed the as-prepared GaN were N-deficient with the N vacancies reaching as much as 21%. Besides single-phase of the hexagonal GaN, no other phase from impurities can be detected under the high-resolution transmission electron microscopy (HRTEM) observations. The room temperature (RT) frequency spectrums of the relative dielectric constants ε_r were measured and the N-deficient GaN exhibited at least twofold enhancement than that of GaN nanostructure materials, especially at low frequency range. Because of the great number of N vacancies (V_N), the rotation direction polarization (RDP) contributes mostly for the enhancement of ε_r in N-deficient GaN.