Solomon Isaac Woods

Transport properties of high-Tc planar Josephson junctions fabricated by nanolithography and ion implantation

We have developed a process for fabrication of planar high-Tc Josephson junctions using nanolithography and a 200 keV ion implanter. Conduction occurs in the ab plane and has no metallurgical interface. Devices may be tuned to operate at temperatures between 1 K and the Tc of the undamaged superconducting material by varying the length of the weak link or by changing the amount of ion damage. We have examined the normal state and superconducting properties of these films and find behavior consistent with a de Gennes dirty limit proximity effect model. Current–voltage curves, Ic(T) and R(T) data suggest a temperature dependent superconducting-normal metal interface that we have incorporated into the proximity effect model.

Planar thin film YBa2Cu3O7−δ Josephson junctions via nanolithography and ion damage

We have developed a process to fabricate planar high-Tc Josephson junctions using nanolithography and a 200 keV ion implanter. Conduction occurs in the ab plane and is interface free. We can systematically tune devices to operate at temperatures between 1 K and the Tc of the undamaged superconducting material by varying the length of the weak link and by changing the amount of ion damage. All of the devices showed clear dc and ac Josephson effects. Measurement of R(T) and Ic(T) of the weak links revealed trends which were consistent with a proximity effect.

Interlayer conductivity in the superconductor Tl 2 Ba 2 CuO 6¿d : Energetics and energy scales

We report on infrared studies of the c-axis electrodynamics of

Stability and uniformity of planar high temperature Josephson junctions fabricated using nanolithography and ion damage

{\mathrm{Tl}}_{2}{\mathrm{Ba}}_{2}{\mathrm{CuO}}_{6+\ensuremath{\delta}}

Investigation of Nd-Ce-Cu-O planar tunnel junctions and bicrystal grain boundary junctions

crystals. A sum-rule analysis reveals spectral weight shifts that can be interpreted as a kinetic energy change at the superconducting transition. In optimally doped crystals, showing an incoherent normal-state response, the kinetic energy is lowered at

Pair tunneling from c-axis YBa2Cu3O7-x to Pb: Evidence for s-wave component from microwave induced steps.

Tl{T}_{c},

DESTRUCTION OF SUPERCONDUCTIVITY IN ND2-XCEXCUO4-DELTA THIN FILMS BY ION IRRADIATION

but no significant change is found in the overdoped samples, which have more coherent conductivity at

Nature of conduction in disordered Nd2-xCexCuO4-Φ films

Tg{T}_{c}.

Systematic Study of Planar Thin Film YBa_2Cu_3O_7-delta Josephson Devices

We have investigated the room temperature stability and the critical current uniformity of planar thin film YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// Josephson junctions. The junctions were fabricated using electron-beam lithography to define a stencil structure followed by ion damage from a conventional 200 keV ion implanter. Using this technique, we have fabricated junctions with weak link lengths of 20-100 nm that showed classical dc and ac Josephson effects at 77 K. By a suitable choice of damage and stencil width, these devices may be tuned to operate at any temperature between 1 K and the bulk transition temperature, and they may be placed anywhere on a wafer, providing a high degree of flexibility for circuit applications. Results obtained over several months showed a high level of room temperature stability, and the uniformity of the junctions was maintained.