a system is provided for the manufacture of carbon based electrical components including , an ultraviolet light source ; a substrate receiving unit whereby a substrate bearing a first layer of carbon based semiconductor is received and disposed beneath the ultraviolet light source ; a mask disposed between the ultraviolet light source and the carbon based semiconductor layer ; a doping agent precursor source ; and environmental chemical controls , configured such that light from the ultraviolet light source irradiates a doping agent precursor and the first carbon layer .