Study of preparation techniques for a practical microbridge dc-SQUID structure fabricated from Nb3Ge

Tests with a small area Nb3Ge dc-SQUID structure revealed promising results: a wide operating temperature range extending up to 20.2 K was achieved with a best modulation depth of 15%. Here we describe development steps towards a more practical device: enlargement of the flux sensitive area and integration of a Nb3Ge coupling coil For this purpose a Nb3Ge multilayer technique was developed using SiO2insulating layers. To optimize the behavior of the very small microbridges the influence of reactive ion etching parameters on the decrease of Tcduring the preparation was studied.