Characteristics of unintentionally doped and lightly Si-doped GaN prepared via pulsed sputtering

We have grown structurally high-quality GaN with a low residual shallow donor concentration (<5 × 1015 cm−3) through pulsed sputtering. Light Si doping to this film with a Si concentration of 2 × 1016 cm−3 leads to the formation of an n-type film with room temperature electron mobility of 1240 cm2V−1s−1, which is comparable to that of the best values for n-type GaN as obtained via conventional growth techniques. At lower temperatures, electron mobility increased, and it reached to 3470 cm2V−1s−1 at 119 K primarily owing to the reduction in the phonon scattering rate. A conventional scattering theory revealed that such high electron mobility in GaN grown via pulsed sputtering can be attributed to the precise control of low-level intentional donors and the reduction in compensating centers. These results are expected to provide significant benefits for future GaN technology by offering high-quality GaN at cost effectively and at low temperatures.