Influence of the environment on the Coulomb blockade in submicrometer normal-metal tunnel junctions

Journal Article · Sat Feb 01 04:00:00 EST 1992 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.45.2950· OSTI ID:7047100

Cleland, A N; Schmidt, J M; Clarke, J ^[1]

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1. Department of Physics, University of California, Berkeley, Berkeley, California 94720 (United States) Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)

Submicrometer normal-metal tunnel junctions were fabricated with thin-film leads of either about 2 k{Omega}/{mu}m or about 30 k{Omega}/{mu}m. The current-voltage ({ital I}-{ital V}) characteristics at millikelvin temperatures displayed a much sharper Coulomb blockade for the high-resistance leads than for the low-resistance leads. The zero-bias differential resistance increased as the temperature was lowered, flattening off at the lowest temperatures. A heuristic model based on the quantum Langevin equation is developed, which explains these effects qualitatively in terms of the Nyquist noise generated in the leads; in this model, the flattening of the zero-bias resistance arises from zero-point fluctuations. The data are also compared with a more accurate phase-correlation model that treats the junction and the circuit coupled to it as a single quantum circuit. This model accounts for the observed {ital I}-{ital V} characteristics quite accurately except near zero bias where it overestimates the dynamic resistance by roughly 50% at the lowest temperatures. This model, however, does not account for the flattening of the zero-bias resistance at the lowest temperatures. It is suggested that the addition of quantum fluctuations in the junction to the phase-correlation theory may account for this discrepancy.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 7047100
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 45:6; ISSN 0163-1829; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

665412* -- Superconducting Devices-- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ELECTRIC CONDUCTIVITY
ELECTRIC CONTACTS
ELECTRICAL EQUIPMENT
ELECTRICAL PROPERTIES
EQUATIONS
EQUIPMENT
FLUCTUATIONS
JUNCTION DIODES
JUNCTIONS
LANGEVIN EQUATION
NOISE
PHYSICAL PROPERTIES
SEMICONDUCTOR DEVICES
SEMICONDUCTOR DIODES
SUPERCONDUCTING JUNCTIONS
TEMPERATURE DEPENDENCE
TUNNEL EFFECT
VARIATIONS