Space charge reconstruction in highly segmented HPGe detectors through capacitance-voltage measurements

Abstract

The space charge distribution inside highly segmented large volume HPGe detectors determined from capacitance–voltage (CV) measurements is investigated. A computer code was developed to understand the impact of impurity concentrations on the resulting capacitances between core contact and outer contact for HPGe detectors biased at different high voltages. The code is intended as a tool for the reconstruction of the doping profile within irregularly shaped detector crystals. The results are validated by comparison with the exact solution of a true coaxial detector. Existing methods for space charge parameter extraction are briefly reviewed. The space charge reconstruction under cylindrical symmetry is derived. An extension of this scheme to higher dimensions for inhomogeneous space charge distributions is illustrated for a two-dimensional segmented coaxial detector.