TY - JOUR

T1 - Conductivity of weakly and strongly localized electrons in a n-type Si/SiGe heterostructure

AU - Shlimak, I.

AU - Ginodman, V.

AU - Levin, M.

AU - Potemski, M.

AU - Maude, D. K.

AU - Gerber, A.

AU - Milner, A.

AU - Paul, D. J.

PY - 2004

Y1 - 2004

N2 - We have investigated the temperature dependence of the longitudinal conductivity a" and Hall resistance Rxy of n-type Si/SiGe heterostructures in the quantum Hall effect regime in magnetic fields up to 23 T. It is shown that for odd integer filling factors i = 3,5,7,9, when the Fermi level EF is situated between the valley-split Landau levels, Δσxx(T) ∝ lnT, which is typical for weakly localized electrons. In the case of even i, when EF lies between spin-split or cyclotron-split levels, σxx(T) is characteristic of strong localization: activation of localized electrons from EF to the nearest mobility edge: σxx ∝ exp[-Δi,T] for i = 6, 10, 12 or variable-range-hopping via localized states in the vicinity of EF: σxx ∝ exp[-(T0i(T)] 1/2 for i = 4, 8. For i = 3, 6, 8, 10, 12, the Hall resistance R xy first overshoots the quantized plateau values h/ie2 and then returns. The explanatory model involves the temporary parallel contribution of the delocalized and weakly localized electrons with different mobilities in the measurement of the Hall voltage Vxy.

AB - We have investigated the temperature dependence of the longitudinal conductivity a" and Hall resistance Rxy of n-type Si/SiGe heterostructures in the quantum Hall effect regime in magnetic fields up to 23 T. It is shown that for odd integer filling factors i = 3,5,7,9, when the Fermi level EF is situated between the valley-split Landau levels, Δσxx(T) ∝ lnT, which is typical for weakly localized electrons. In the case of even i, when EF lies between spin-split or cyclotron-split levels, σxx(T) is characteristic of strong localization: activation of localized electrons from EF to the nearest mobility edge: σxx ∝ exp[-Δi,T] for i = 6, 10, 12 or variable-range-hopping via localized states in the vicinity of EF: σxx ∝ exp[-(T0i(T)] 1/2 for i = 4, 8. For i = 3, 6, 8, 10, 12, the Hall resistance R xy first overshoots the quantized plateau values h/ie2 and then returns. The explanatory model involves the temporary parallel contribution of the delocalized and weakly localized electrons with different mobilities in the measurement of the Hall voltage Vxy.

UR - http://www.scopus.com/inward/record.url?scp=2342578235&partnerID=8YFLogxK

U2 - 10.1002/pssc.200303643

DO - 10.1002/pssc.200303643

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AN - SCOPUS:2342578235

SN - 1610-1634

VL - 1

SP - 67

EP - 70

JO - Physica Status Solidi C: Conferences

JF - Physica Status Solidi C: Conferences

IS - 1

ER -