Characteristics of ion-implanted contacts for nuclear particle detectors: I. Window thickness of ion-implanted semiconductor detectors

Abstract

The thickness of the entrance window of ion-implanted semiconductor counters was experimentally studied by pulse height defect measurements. It was found that the window thickness D strongly depends on the reverse voltage U A. This dependence may be described by the function U A = F( D) − η . The influenceof the doping concentration of the base material, energy of the implanted ions, total number of implanted ions, annealing temperature, and crystal orientation. For boron-implanted contacts a formula is given that describes the measured results within 20%. Under certain conditions extremely thick windows up to 10 μm were found. In high resistiity material (100000 ohm·cm) for example thin windows (<0.02 μm) require high reverse voltage (≈600 V); whereas in silicon with a resistivity smaller than 10000 ohhm·cm, thin windows can easily be obtained even at small detector bias.