P-TYPE SILICON DRIFT DETECTORS - FIRST RESULTS

We have fabricated a 4 cm x 4 cm, position-sensitive silicon drift det ector using high purity, p-type silicon as the substrate. In this pape r, we describe the double-sided planar process used to fabricate the d etectors and the strategy used to suppress surface carrier inversion d ue to the presence of fixed positive charge at the Si/SiO2 interface. The key issue in optimizing the fabrication process has been to minimi ze leakage currents and prevent breakdown at low voltages. Tests show that a drift signal can be measured across the entire length of the de tector and that the transit time of the holes varies linearly with the position of the induced charge signal.