p-type silicon drift detectors: first results

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