Electrical properties of Si-doped GaN prepared using pulsed sputtering

摘要

In this study, we investigated the basic electrical properties of Si-doped wurtzite GaN films prepared using a low-temperature pulsed sputtering deposition (PSD) process. We found that the electron concentration can be controlled in the range between 1.5 x 10~(16) and 2.0 × 10~(20)cm~(-3). For lightly Si-doped GaN ([Si] = 2.1 × 10~(16)cm~(-3)), the room temperature (RT) electron mobility was as high as 1008 cm~2V~(-1)s~(-1), which was dominantly limited by polar optical phonon scattering. Moreover, we found that heavily Si-doped GaN prepared using PSD exhibited an RT mobility as high as 110cm~2V~(-1)s~(-1) at an electron concentration of 2 × 10~(20)cm~(-3), which indicated that the resistivity of this film was almost as small as those of typical transparent conductive oxides such as indium tin oxide. At lower temperatures, the electron mobility increased to 1920 cm~2V~(-1) s~(-1) at 136 K, and the temperature dependence was well explained by conventional scattering models. These results indicate that Si-doped GaN prepared using PSD is promising not only for the fabrication of GaN-based power devices but also for use as epitaxial transparent electrode materials for nitride based optical devices.