The influence of the drive layer thickness in ion implanted bubble circuits

The effect of the implanted layer thickness in Y Sm Iu Ca Ge garnet films supporting 2 μm bubbles has been investigated by using H+, He and Ne ions. Single and multiple ion implantations at energies up to 200 KeV have been employed in order to achieve thicknesses varying from 0.2 μm to 0.7 μm. The damage profiles have been measured by chemical acid etching. Homogeneously implanted regions can be created by using either H+ or He and Ne ions. Propagation margins have been measured on circuits defined by patterns protected from ion implantation. Good results are obtained for thicknesses larger than 0.4 μm ; no bubble motion is possible under 0.3 μm. The minimum thickness for bubble propagation is in the range of 0.3 μm for 2 μm bubbles, optimum margins are obtained for 0.6 μm.