| Autor: |
Tolpygo, S.K., Cimpoiasu, E., Liu, X., Simonian, N., Polyakov, Yu.A., Lukens, J.E., Likharev, K.K. |
| Předmět: |
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| Zdroj: |
IEEE Transactions on Applied Superconductivity; Jun2003 Part 1 of 3, Vol. 13 Issue 2, p99, 4p, 2 Charts, 6 Graphs |
| Abstrakt: |
We have measured dc I-V curves of niobium-trilayer (Nb/Al/AlO[sub ℵ]/Nb) junctions with barriers thermally grown within a broad range of oxygen exposure E = Pt, from 2 × 10[sup 5] to 2 × 10[sup 9] Pa-s, and for applied electric fields ranging from zero all the way up to the breakdown — typically, above 10 MV/cm. The data can be reasonably well fitted by the direct theory assuming trapezoidal barrier profile and using the numerical solution of the Schrödinger equation. (The traditional WKB approximation gives considerable errors for barriers so thin and sharp.) The fitting has shown that with the increase of oxygen exposure, the effective oxide thickness d[sub ef] ≡ (m/m[sub 0])[sup ∞]d (where m is the effective mass of the tunneling electron and (α ≈ 0.51) grows from 0.83 to 1.08 nm, while the average barrier height grows from 1.7 to 1.9 eV, and the zero-voltage conductance G[sub 0] continues to drop as E[sup -1/2] through all the studied exposure range. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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