The Effect of Space Charge due to the Auto-Ionization of Neutral, Hydrogenic States in Point-Contact Germanium Detectors at MilliKelvin Temperatures

D. Faiez[1], N. Mirabolfathi[1], B. Sadoulet[1], K. M. Sundqvist[2]
[1]Department of Physics, University of California - Berkeley, Berkeley, CA, USA
[2]Department of Electrical & Computer Engineering, Texas A&M University, College Station, TX, USA
Published in 2014

A class of semiconducting detectors, operated at temperature T~50mK, has direct application to the search for dark matter particle, when are able to simultaneously measure both the ionization and phonons created by particle interactions.

We explore the effect of space charge accumulation in a germanium p-type point contact detector which arises due to the auto-ionization of hydrogenic acceptors subject to high, applied electric fields. This was performed using the PDE interface and the AC/DC Module.

The results from our simulations lead us to believe that, perhaps with an intentional, regional introduction of the correct impurity type and concentration, we may be able to mitigate unwanted voltage breakdown effects due to high fields near the contact electrodes.

Download