Electroluminescence of diamond films induced by a scanning tunneling microscope

We report the scanning tunneling microscope induced band-A emission from boron-doped polycrystalline diamond films fabricated by chemical-vapor deposition (CVD). The broad blue emission occurs at a bias above ±3.4 V with double peaks at 410 and 450 nm and is attributed to the dislocation-related defect centers. Greatly enhanced green emissions around 530 nm are observed at high positive bias. This, together with strongly bias- and polarity-dependent emission intensities and spectra, leads us to propose that the boost in the green emission at high bias is probably related to the minority electron injection into the boron-related acceptor states in the subsurface.