Control of Al-implantation doping in 4H–SiC

We report results of high-dose Al-ion implantation in 4H–SiC. Using multiple energy implantation techniques, box profiles were realized with targeted concentrations: 3.33×1018 to 1021 cm−3. The depths were 190 and 420 nm. The implantation energies ranged from 30 to 200 keV. The implantation and annealing temperatures were 650 and 1670°C, respectively. First, infrared investigations were done to assess the surface quality of the samples before and after annealing. Next, the conduction mechanism was investigated. Performing Hall measurements, we found that the room temperature free hole concentration varies like pH=Ct/105 (cm−3), where Ct is the targeted Al-concentration, with a high level of electronic mobility. For the targeted concentration 1021 cm−3, this resulted in an active layer with 95 mΩ cm resistivity and, at room temperature, a free hole concentration of 1019 cm−3.