Improved p-type Conductivity in Heavily, Al-doped SiC by Ion-Beam- Induced Nano-Crystallization

Low-resistivity ( < 0.1 Ohm cm at room temperature), p-type SiC layers were produced by the combination of high dose Al implantation in n-type, 6H-SiC at low temperature, subsequent ion-beam-induced crystallization by means of Si irradiation at 500°C and high temperature annealing at 1500°C. The implanted SiC layers have a nanocrystalline structure consisting of randomly oriented grains of 3C-SiC. The electrical properties of the nanocrystalline and single-crystalline reference samples were investigated by sheet resistance and Hall measurements in dependence on temperature. In comparison with the standard doping process the hole concentration is enhanced by more than one order of magnitude. This can be explained by a higher solid solubility of Al in nanocrystalline SiC. Current-voltage measurements across the vertical p-n-junction in the heavily doped nanocrystalline and single-crystalline samples demonstrated the equivalence of the diode quality.