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Advances in Condensed Matter Physics
Volume 2017, Article ID 5038462, 12 pages
https://doi.org/10.1155/2017/5038462
Research Article

Low Temperature Conductivity in -Type Noncompensated Silicon below Insulator-Metal Transition

1Belarusian State University of Informatics and Radioelectronics, P. Browka 6, 220013 Minsk, Belarus
2Belarusian State University, Nezalezhnastsi Av. 4, 220030 Minsk, Belarus
3National Research Nuclear University (MEPHI), Kashirskoe Highway 31, Moscow 115409, Russia

Correspondence should be addressed to S. L. Prischepa; yb.riusb@apehcsirp

Received 17 November 2016; Revised 4 January 2017; Accepted 22 January 2017; Published 14 February 2017

Academic Editor: Da-Ren Hang

Copyright © 2017 A. L. Danilyuk et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We investigate the transport properties of -type noncompensated silicon below the insulator-metal transition by measuring the electrical and magnetoresistances as a function of temperature for the interval 2–300 K. Experimental data are analyzed taking into account possible simple activation and hopping mechanisms of the conductivity in the presence of two impurity bands, the upper and lower Hubbard bands (UHB and LHB, resp.). We demonstrate that the charge transport develops with decreasing temperature from the band edge activation (110–300 K) to the simple activation with much less energy associated with the activation motion in the UHB (28–90 K). Then, the Mott-type variable range hopping (VRH) with spin dependent hops occurs (5–20 K). Finally, the VRH in the presence of the hard gap (HG) between LHB and UHB (2–4 K) takes place. We propose the empiric expression for the low density of states which involves both the UHB and LHB and takes into account the crossover from the HG regime to the Mott-type VRH with increasing temperature. This allows us to fit the low experimental data with high accuracy.