Investigation of the electrical conduction mechanisms in P-type amorphous germanium electrical contacts for germanium de
- PDF / 1,894,400 Bytes
- 10 Pages / 595.276 x 790.866 pts Page_size
- 69 Downloads / 205 Views
Special Article - Tools for Experiment and Theory
Investigation of the electrical conduction mechanisms in P-type amorphous germanium electrical contacts for germanium detectors in searching for rare-event physics S. Bhattarai, R. Panth, W.-Z. Wei, H. Mei, D.-M. Meia , M.-S. Raut, P. Acharya, G.-J. Wang Department of Physics, University of South Dakota, 414 E Clark St, Vermillion, SD 57069, USA
Received: 24 March 2020 / Accepted: 7 October 2020 © The Author(s) 2020
Abstract For the first time, electrical conduction mechanisms in the disordered material system is experimentally studied for p-type amorphous germanium (a-Ge) used for high-purity Ge detector contacts. The localization length and the hopping parameters in a-Ge are determined using the surface leakage current measured from three high-purity planar Ge detectors. The temperature dependent hopping distance and hopping energy are obtained for a-Ge fabricated as the electrical contact materials for high-purity Ge planar detectors. As a result, we find that the hopping energy in a-Ge increases as temperature increases while the hopping distance in a-Ge decreases as temperature increases. The ◦ localization length of a-Ge is on the order of 2.13−0.05 +0.07 A −0.83 ◦ to 5.07+2.58 A , depending on the density of states near the Fermi energy level within bandgap. Using these parameters, we predict that the surface leakage current from a Ge detector with a-Ge contacts can be much smaller than one yocto amp (yA) at helium temperature, suitable for rare-event physics searches.
1 Introduction The nature of dark matter and the properties of neutrinos are the important questions of physics beyond the Standard Model of particle physics and remains elusive. Thus, understanding their properties has become an important aspect of underground physics. Numerous research groups are trying to understand their properties by various detection techniques This work was supported in part by NSF NSF OISE 1743790, NSF PHYS 1902577, NSF OIA 1738695, DOE Grant DE-FG02-10ER46709, DE-SC0004768, the Office of Research at the University of South Dakota and a research center supported by the State of South Dakota. a e-mail:
[email protected] (corresponding author)
0123456789().: V,-vol
and detection materials [1–9]. Interaction between dark matter and ordinary matter as a target occurs only through a weakly elastic scattering process, which leaves a very small energy deposition from nuclear or electronic recoils [10]. This requires detectors to have a very low-energy threshold. Germanium (Ge) detectors are excellent in the search for dark matter [6,11–13], since Ge detectors offer the lowest energy threshold among the current detector technologies. Also, due to its excellent energy resolution and ability to minimize the background from two neutrino double-beta (2νββ) decay, Ge detectors are highly preferred for observing neutrinoless double-beta (0νββ) decay [14]. Hence, the high-purity Ge (HPGe) crystals are widely used as detectors for rare event physics. Many research groups like
Data Loading...
