Characteristics of boron in as-grown 4H-SiC layers produced by fast epitaxy, i.e. sublimation and vertical hot-wall CVD, were studied by electrical and optical measurements. The boron-related contribution to the net acceptor concentration in the layers (as determined by CV on p-type residual doped sublimation epitaxy layers), the presence of deep boron centers (as indicated by DLTS) and boron-related "green" emission at similar to 505 nm (as observed by CL) are detected for various growth temperatures and C/Si ratios. The results are discussed in relation with the C vacancies in the lattice that may be affected by growth rate and input C/Si ratio in the CVD process.