Berkeley Lab

Optimization of Fabrication Process Parameters for High-Purity Germanium Detectors

PI: Kai Vetter
Staff: Quinn Looker, Mark Amman

High-Purity Germanium Detectors represent the gold standard in energy resolution due to superior charge transport properties and refined crystal growth procedures.  Room for progress yet remains in improving the electrical contacts as doped contacts may be excessively thick, as with a Li-diffused contact, giving a large dead layer.  Modern advances in segmentation require varied and sometimes complex electrode configurations, with segmentation requiring additional processing steps.  Amorphous semiconductor contacts allow a simplified fabrication process due to their alternate use as a passivation layer, and allow flexibility due to their ability to block electron and hole injection.  This work comprises a systematic study of charge injection barrier height, temperature cycling stability, and surface channel behavior as a function of processing conditions, including material, sputter pressure, hydrogen inclusion, and film thickness



Relevant publications:
P. N. Luke et. al., “Amorphous Ge Bipolar Blocking Contacts on Ge Detectors.” IEEE TNS Vol. 39, No. 4 (1992).
M. Amman, P. N. Luke, S. E. Boggs, “Amorphous-semiconductor-contact germanium-based detectors for gamma-ray imaging and spectroscopy.” NIM A 579 (2007).