Low-dose implants of Al and B were characterized in p-type 4H- and 6H-SiC after annealing at 1300 to 1600C. In contrast to previous studies of heavily doped p-type layers, a study was made here of more lightly-doped layers. The activation rates of the implanted ions, the depth profiles resulting from secondary ion mass spectroscopy, and surface roughness data obtained using atomic force microscopy were presented as a function of the annealing temperature. The temperature dependence of the free hole density and hole mobility were characterized by using Hall-effect measurements. After annealing at 1600C, usable device-quality p-type layers were obtained for both SiC polytypes and both implanted species. After annealing at, or below, about 1500C, the implanted layers had a much higher sheet resistivity due to the presence of unannealed compensating defects. These layers were not of device quality. The B-implanted layers exhibited a higher mobility, while the activation of implanted Al was much higher and more uniform.

Low-Dose Aluminum and Boron Implants in 4H and 6H Silicon Carbide. N.S.Saks, A.K.Agarwal, S.H.Ryu, J.W.Palmour: Journal of Applied Physics, 2001, 90[6], 2796-805