The electrochemical capacitance-voltage profiling (eCV) technique is employed to measure the carrier concentration in heavily boron-doped Si, grown by molecular beam epitaxy. Secondary ion mass spectrometry (SIMS) and Hall measurements are also carried out for comparison. The carrier concentrations obtained by eCV match well with the Hall measurements. The results indicate that the eCV technique is capable of probing carrier concentrations well into the 10(20) cm(-3) range with a good precision. The relative merits of the eCV and SIMS depth profiling are shown to be useful in the cm analysis of boron incorporation behaviour at doping levels above solubility limits.