Comparison of temperature-dependent resistivity of heavily Al- and N-codoped 4H-SiC grown by physical vapor transport and heavily Al-doped 4H-SiC grown by chemical vapor deposition

The temperature-dependent resistivity of heavily Al- and N-codoped 4H-SiC grown by physical vapor transport (PVT) with Al concentrations (C Al) higher than 1019 cm-3 is investigated to obtain high-growth-rate and low-cost p+-type substrates suitable for the collectors of n-channel insulated-gate bipolar transistors. The resistivity is compared with that of heavily Al-doped 4H-SiC grown by CVD. In the band conduction region, the hole mobility of the PVT-grown codoped samples is slightly lower than that of the CVD-grown sample at the same C Al. At C Al values of around 2 x 1020 cm-3, the temperature range in the variable-range-hopping conduction region for the PVT-grown codoped samples is much wider than that for the CVD-grown samples.