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Title: Imaging the oblique propagation of electrons in germanium crystals at low temperature and low electric field

Abstract

Excited electrons in the conduction band of germanium collect into four energy minima, or valleys, in momentum space. These local minima have highly anisotropic mass tensors which cause the electrons to travel in directions which are oblique to an applied electric field at sub-Kelvin temperatures and low electric fields, in contrast to the more isotropic behavior of the holes. This experiment produces a full two-dimensional image of the oblique electron and hole propagation and the quantum transitions of electrons between valleys for electric fields oriented along the [0,0,1] direction. Charge carriers are excited with a focused laser pulse on one face of a germanium crystal and then drifted through the crystal by a uniform electric field of strength between 0.5 and 6 V/cm. The pattern of charge density arriving on the opposite face is used to reconstruct the trajectories of the carriers. Measurements of the two-dimensional pattern of charge density are compared in detail with Monte Carlo simulations developed for the Cryogenic Dark Matter Search (SuperCDMS) to model the transport of charge carriers in high-purity germanium detectors.

Authors:
; ; ; ; ; ;  [1];  [1];  [2]; ; ;  [3]; ; ;  [4]
  1. Department of Physics, Stanford University, Stanford, California 94305 (United States)
  2. (United States)
  3. SLAC National Accelerator Facility, Menlo Park, California 94025 (United States)
  4. Department of Physics, University of California, Berkeley, California 94720 (United States)
Publication Date:
OSTI Identifier:
22489284
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 108; Journal Issue: 2; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CHARGE CARRIERS; CHARGE DENSITY; CRYSTALS; ELECTRIC FIELDS; ELECTRONS; GE SEMICONDUCTOR DETECTORS; HOLES; MONTE CARLO METHOD; TRAJECTORIES; TWO-DIMENSIONAL SYSTEMS

Citation Formats

Moffatt, R. A., E-mail: rmoffatt@stanford.edu, Cabrera, B., Corcoran, B. M., Kreikebaum, J. M., Redl, P., Shank, B., Yen, J. J., Young, B. A., Department of Physics, Santa Clara University, Santa Clara, California 95053, Brink, P. L., Cherry, M., Tomada, A., Phipps, A., Sadoulet, B., and Sundqvist, K. M. Imaging the oblique propagation of electrons in germanium crystals at low temperature and low electric field. United States: N. p., 2016. Web. doi:10.1063/1.4939753.
Moffatt, R. A., E-mail: rmoffatt@stanford.edu, Cabrera, B., Corcoran, B. M., Kreikebaum, J. M., Redl, P., Shank, B., Yen, J. J., Young, B. A., Department of Physics, Santa Clara University, Santa Clara, California 95053, Brink, P. L., Cherry, M., Tomada, A., Phipps, A., Sadoulet, B., & Sundqvist, K. M. Imaging the oblique propagation of electrons in germanium crystals at low temperature and low electric field. United States. doi:10.1063/1.4939753.
Moffatt, R. A., E-mail: rmoffatt@stanford.edu, Cabrera, B., Corcoran, B. M., Kreikebaum, J. M., Redl, P., Shank, B., Yen, J. J., Young, B. A., Department of Physics, Santa Clara University, Santa Clara, California 95053, Brink, P. L., Cherry, M., Tomada, A., Phipps, A., Sadoulet, B., and Sundqvist, K. M. 2016. "Imaging the oblique propagation of electrons in germanium crystals at low temperature and low electric field". United States. doi:10.1063/1.4939753.
@article{osti_22489284,
title = {Imaging the oblique propagation of electrons in germanium crystals at low temperature and low electric field},
author = {Moffatt, R. A., E-mail: rmoffatt@stanford.edu and Cabrera, B. and Corcoran, B. M. and Kreikebaum, J. M. and Redl, P. and Shank, B. and Yen, J. J. and Young, B. A. and Department of Physics, Santa Clara University, Santa Clara, California 95053 and Brink, P. L. and Cherry, M. and Tomada, A. and Phipps, A. and Sadoulet, B. and Sundqvist, K. M.},
abstractNote = {Excited electrons in the conduction band of germanium collect into four energy minima, or valleys, in momentum space. These local minima have highly anisotropic mass tensors which cause the electrons to travel in directions which are oblique to an applied electric field at sub-Kelvin temperatures and low electric fields, in contrast to the more isotropic behavior of the holes. This experiment produces a full two-dimensional image of the oblique electron and hole propagation and the quantum transitions of electrons between valleys for electric fields oriented along the [0,0,1] direction. Charge carriers are excited with a focused laser pulse on one face of a germanium crystal and then drifted through the crystal by a uniform electric field of strength between 0.5 and 6 V/cm. The pattern of charge density arriving on the opposite face is used to reconstruct the trajectories of the carriers. Measurements of the two-dimensional pattern of charge density are compared in detail with Monte Carlo simulations developed for the Cryogenic Dark Matter Search (SuperCDMS) to model the transport of charge carriers in high-purity germanium detectors.},
doi = {10.1063/1.4939753},
journal = {Applied Physics Letters},
number = 2,
volume = 108,
place = {United States},
year = 2016,
month = 1
}
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