Schematic view of a JJ indicating the characteristic lengths in the , , and directions. The slit width in the PMMA photoresist mask is the key factor. The top frame shows a picture of an array of 14 JJ. The dark gray parts are superconducting microbridges; the small black lines, the diffraction limited traces of the 20 nm slits; and the white areas are gold contact pads.
Resistance (full lines) and critical current (dash line) vs temperature for several JJ irradiated with , 3, 4.5, and . Up to 6 JJ per dose have been represented. For a given dose , a coupling temperature and a dispersion can be defined.
Calculated LDD (circles) and ILDD (squares) for O and He of 100 keV. The ILDD have been normalized by the slits width and curves have been multiplied by different factors indicated in the figure for the sake of clarity. The lines are guides for the eyes.
The spread in vs the quantity (see text). Experimental data for 100 keV oxygen irradiation and a slit of nominal width 20 nm (closed symbol) align on a straight line. The proposed model (open symbol) quantitatively accounts for them if an uncertainty of on the slit width is used.
Calculated as function of (see text) for He, O, and Ar irradiations at different energies, using i.e., slit sizes and . The different lines correspond to linear fits according to the model proposed, for different . For and 74.1 K, simulations were performed for an irradiation with oxygen ions only.
Calculated lateral distribution width as a function of the irradiation energy for He, O, and Ar ions. The lines are a guide for the eyes. The inset shows a representation of the lateral damage distribution as a function of thickness for high energy irradiation (He at 100 keV), for a 100 nm thick YBCO film on STO.
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