We studied the properties of Si doped (11-20) a-plane GaN with two different buffer layers. The crystal quality of a-plane GaN is improved when a multi buffer (MB) rather than a conventional buffer (CB) layer is used. To study the effect of Si doping, the SiH4 flow rate was varied from 0.9 to 40 sccm. As the flow rate is increased, both the carrier concentration and mobility are observed to increase. This arises owing to a change in the dominant scattering mechanism from defect and ionized scattering. The temperature dependent hall measurements show that the change in the scattering mechanism from dislocation to phonon scattering results from differences in the crystal quality between the samples.

Keywords: Nonpolar GaN; Si-doping; Scattering mechanism; Metalorganic chemical vapor deposition