OBIC MEASUREMENTS ON PLANAR HIGH-VOLTAGE P(+)-N JUNCTIONS WITH DIAMOND-LIKE CARBON-FILMS AS PASSIVATION LAYER

Diamond-like carbon (DLC) films (a-C:H) have been deposited on planar p+-n junctions in silicon for electroactive passivation. The films have been, produced by an r.f. plasma discharge with various self-bias voltages. The DLC-coated devices show improved blocking characteristics compared with uncoated samples. In order to study the influence of DLC films on planar p+-n junctions, we have measured the local induced photoconductivity (OBIC, optical-beam-induced current). By using light with a wavelength of 500 nm, the space charge region near the interface has been investigated. We are able to correlate the observed changes in the surface space charge region due to the DLC coating with the improved blocking characteristics.