Diamond/silicon heterojunctions (DSHJs) and related characteristics have been studied. Heterojunctions can be obtained by growing p-type diamond films (DFs) on p-type silicon substrates to form homotype (p-p) DSHJs; or by growing p-type diamond films on n-type silicon substrates to form heterotype (p-n) DSHJs via the route of chemical vapor deposition (CVD). DSHJs have been characterized by studying current-voltage ( I–V) curves which showed rectifying. These DSHJ curves are different from those produced by metal/diamond junctions.