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Title: Hopping conduction in uniaxially stressed Si:B near the insulator-metal transition

Abstract

Using uniaxial stress to tune the critical density near that of the sample, we have studied in detail the low-temperature conductivity of p-type Si:B in the insulating phase very near the metal-insulator transition. For all values of temperature and stress, the conductivity collapses onto a single universal curve, {sigma}(S,T)=AT{sup 1/2}F[T{sup {asterisk}}(S)/T]. For large values of the argument, the scaling function F[T{sup {asterisk}}(S)/T] is well fit by exp[{minus}(T{sup {asterisk}}/T){sup 1/2}], the exponentially activated form associated with variable-range hopping when electron-electron interactions cause a soft Coulomb gap in the density of states at the Fermi energy. The temperature dependence of the prefactor, corresponding to the T dependence of the critical curve, has been determined reliably for this system, and is {proportional_to}T{sup 0.5}. We show explicitly that neglecting the prefactor leads to substantial errors in the determination of the T{sup {asterisk}}{close_quote}s and the critical exponents derived from them. The conductivity is not consistent with Mott variable-range hopping, exp[{minus}(T{sup {asterisk}}/T){sup 1/4}], in the critical region, nor does it obey this form for any range of the parameters. Instead, the conductivity of Si:B is well fit by {sigma}=AT{sup 1/2}&hthinsp;exp[{minus}(T{sup {asterisk}}/T){sup {alpha}}] for smaller argument of the scaling function, with {alpha}=0.31 related to the critical exponentsmore » of the system at the metal-insulator transition. {copyright} {ital 1999} {ital The American Physical Society}« less

Authors:
; ; ;  [1];  [2]
  1. Physics Department, City College of the City University of New York, New York, New York 10031 (United States)
  2. Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544-5263 (United States)
Publication Date:
OSTI Identifier:
357609
Resource Type:
Journal Article
Journal Name:
Physical Review, B: Condensed Matter
Additional Journal Information:
Journal Volume: 60; Journal Issue: 4; Other Information: PBD: Jul 1999
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BORON; FERMI LEVEL; SILICON; DOPED MATERIALS; BORON ADDITIONS; ELECTRIC CONDUCTIVITY; TEMPERATURE DEPENDENCE; STRESSES; SCALING; ELECTRON-ELECTRON INTERACTIONS; ENERGY GAP

Citation Formats

Bogdanovich, S, Simonian, D, Kravchenko, S V, Sarachik, M P, and Bhatt, R N. Hopping conduction in uniaxially stressed Si:B near the insulator-metal transition. United States: N. p., 1999. Web. doi:10.1103/PhysRevB.60.2286.
Bogdanovich, S, Simonian, D, Kravchenko, S V, Sarachik, M P, & Bhatt, R N. Hopping conduction in uniaxially stressed Si:B near the insulator-metal transition. United States. doi:10.1103/PhysRevB.60.2286.
Bogdanovich, S, Simonian, D, Kravchenko, S V, Sarachik, M P, and Bhatt, R N. Thu . "Hopping conduction in uniaxially stressed Si:B near the insulator-metal transition". United States. doi:10.1103/PhysRevB.60.2286.
@article{osti_357609,
title = {Hopping conduction in uniaxially stressed Si:B near the insulator-metal transition},
author = {Bogdanovich, S and Simonian, D and Kravchenko, S V and Sarachik, M P and Bhatt, R N},
abstractNote = {Using uniaxial stress to tune the critical density near that of the sample, we have studied in detail the low-temperature conductivity of p-type Si:B in the insulating phase very near the metal-insulator transition. For all values of temperature and stress, the conductivity collapses onto a single universal curve, {sigma}(S,T)=AT{sup 1/2}F[T{sup {asterisk}}(S)/T]. For large values of the argument, the scaling function F[T{sup {asterisk}}(S)/T] is well fit by exp[{minus}(T{sup {asterisk}}/T){sup 1/2}], the exponentially activated form associated with variable-range hopping when electron-electron interactions cause a soft Coulomb gap in the density of states at the Fermi energy. The temperature dependence of the prefactor, corresponding to the T dependence of the critical curve, has been determined reliably for this system, and is {proportional_to}T{sup 0.5}. We show explicitly that neglecting the prefactor leads to substantial errors in the determination of the T{sup {asterisk}}{close_quote}s and the critical exponents derived from them. The conductivity is not consistent with Mott variable-range hopping, exp[{minus}(T{sup {asterisk}}/T){sup 1/4}], in the critical region, nor does it obey this form for any range of the parameters. Instead, the conductivity of Si:B is well fit by {sigma}=AT{sup 1/2}&hthinsp;exp[{minus}(T{sup {asterisk}}/T){sup {alpha}}] for smaller argument of the scaling function, with {alpha}=0.31 related to the critical exponents of the system at the metal-insulator transition. {copyright} {ital 1999} {ital The American Physical Society}},
doi = {10.1103/PhysRevB.60.2286},
journal = {Physical Review, B: Condensed Matter},
number = 4,
volume = 60,
place = {United States},
year = {1999},
month = {7}
}