Synthesis and optical properties of vertically aligned ZnO nanorods

ZnO nanorods were grown on an n-type silicon (111) substrate with the assistance of Au catalyst by chemical vapor deposition (CVD). The ZnO nanorods were about 200 nm diameter with uniform lengths of about 1.2 microm. The ZnO nanorods exhibited [0001] orientation. ZnO nanorods grow in dense arrays perpendicular to the (111)-plane of silicon due to [0001]ZnO perpendicular [111]Si, [2110]ZnO perpendicular [110]Si, [1210]ZnO perpendicular [101]Si and [1120]ZnO perpendicular [011]Si epitaxy. Room-temperature photoluminescence (PL) measurements show three near band-edge emission peak at 377, 379, 389 nm. These peaks are attributed to exciton transitions. Analysis indicates that the band gap of ZnO nanorods is 3.301 eV and exciton binding energy is 0.114 eV.