Low-field transport properties and scattering mechanisms of degenerate n-GaN by sputtering from a liquid Ga target

In this work, degenerate n-type GaN thin films prepared by co-sputtering from a liquid Ga-target were demonstrated and their low-field scattering mechanisms are described. Extremely high donor concentrations above 3 × 10 (20) cm (-3) at low process temperatures (< 800 °C) with specific resistivities below 0.5 mΩcm were achieved. The degenerate nature of the sputtered films was verified via temperature-dependent Hall measurements (300-550 K) revealing negligible change in electron mobility and donor concentration. Scattering at ionized impurities was determined to be the major limiting factor with a minor contribution of polar optical-phonon scattering at high temperatures.