Analysis of the hole transport through valence band states in heavy Al doped 4H-SiC by ion implantation

The temperature dependence of the Hall hole density and the Hall mobility data of heavy doped p-type 4H-SiC(Al) materials obtained by Al_ ion implantation have been analysed in the frame of the charge neutrality condition and the relaxation time approximation. Samples with implanted Al concentrations in the range 10(19) -10(20) cm(-3) and 1950 degrees C/5 min conventional annealing have been taken into account. The reliability of the calculation has been critically discussed by focusing the attention on both the validity limits of the models for the impurity scattering mechanisms and the adopted Hall factor. By introducing empirical mass anisotropy factors, reasons were given in favour of a generalized use of the unique experimental evaluation of the Hall factor reported by the literature for p-type 4H-SiC, assessed for an Al acceptor density in the range of 1.8 x 10(15) cm(-3) -2 x 10(18) cm(-3). The simultaneous fits of the Hall hole density and mobility data indicate an electrical activation of the Al impurities of the order or higher than 70% and a compensation of about 10% of the Al acceptors. (C) 2013 AIP Publishing LLC.