Observation of fluctuation-induced tunneling conduction in micrometer-sized tunnel junctions

Abstract

Micrometer-sized Al/AlOx/Y tunnel junctions were fabricated by the electron-beam lithography technique. The thin (≈ 1.5–2 nm thickness) insulating AlOx layer was grown on top of the Al base electrode by O2 glow discharge. The zero-bias conductances G(T) and the current-voltage characteristics of the junctions were measured in a wide temperature range 1.5–300 K. In addition to the direct tunneling conduction mechanism observed in low-G junctions, high-G junctions reveal a distinct charge transport process which manifests the thermally fluctuation-induced tunneling conduction (FITC) through short nanoconstrictions. We ascribe the experimental realization of the FITC mechanism to originating from the formations of “hot spots” (incomplete pinholes) in the AlOx layer owing to large junction-barrier interfacial roughness

Reduced resistance drift in tunnel junctions using confined tunnel barriers

“…25 Furthermore, the device resistance as a function of temperature increases ≈ 20 % with decreasing temperature (300 K to 4 K) and fits a G ∝ T 2 relationship well, supporting our interpretation of high quality barriers with minimal pinhole formation. 26,27 The resistance values shown are corrected for a “negative resistance” artifact known to occur in crossed wire geometries. 28 The initial RA products of these devices are (3.1 ± 0.7) × 10 4 Ω· µ m 2 for confined and (7.3 ± 2.2) × 10 4 Ω· µ m 2 for unconfined.…”

Collective charge transport in semiconductor-metal hybrid nanocomposite

“…The microscopic mechanism of such phenomenon is not yet well-understood and cannot be explained by a single theoretical framework. [27][28][29][30][31][32] Therefore, our observation of quantum tunneling and VRH at different temperatures is not unexpected but presents a special case for forming a better understanding of electronic conduction mechanism in hybrid nanosystems.…”

“…29 However, with increase in temperature, step-like non-linearity of the I-V curve vanishes. 30,31 Our operating temperature being relatively high (!77 K), we do not expect to observe FITC or multi-step tunneling of tightly confined electronic states in NPs. 32 Nevertheless, large random thermal voltages fluctuating across the insulating gap, 31 similar to FITC could influence the conduction mechanism differently at different temperature ranges thereby contributing to the observed phenomenon.…”

Influence of Ultraviolet/Ozonolysis Treatment of Nanocarbon Filler on the Electrical Resistivity of Epoxy Composites

“…In the classical model of percolation, power dependence of conductivity on the filler content essentially reflects only the increase in the number of conductive chains N * chain_in_CM . Therefore, to describe the behavior of electrical characteristics depending on concentration, temperature, etc., a model of effective electrical conductivity, based on consideration of the value of contact resistance between the conductive filler particles R к has been proposed in [ 31 ].…”