Processing of all-NbN tunnel junction series arrays

The processing of an all-NbN tunnel junction with an aluminum oxide barrier system is reported. A NbN/Al
2
O
3
/NbN trilayer was deposited by dc magnetron sputtering with the oxide barrier formed by ion beam oxidation. Individual junctions and series arrays were patterned using reactive ion etching and conventional photolithography, 100 junction (10 × 10 μm
²
) series arrays have been demonstrated with good tunneling Characteristics showing low leakage (V
^m
> 20) and acceptable currest densities.