Ion beam induced charge technique has been used in order to investigate the charge collection properties of 4H-SiC epitaxial Schottky barrier nuclear detectors. In this work, 2 MeV He ions microbeam about 2 mum spot size scanned the total surface area of the detector in order to obtain maps of the charge collection efficiency (CCE) at different bias voltages. The maps turned out to be very homogeneous, with the conclusion that energy resolution of the detectors is not affected by nonhomogeneous broadening due to fluctuations of CCE. Fitting the experimental data obtained for low bias voltages corresponding to depletion layer widths narrower than He ions range-was possible only by including the contribution of diffusion. By this way, holes diffusion length was determined to be 2 mum.