We have fabricated YBa 2 Cu 3 O 7 - x ramp-edge junctions with surface-modified barriers on a ground plane. The fabricated junctions exhibited current-voltage characteristics that were consistent with the resistive-shunted-junction model up to 70 K. However, the critical temperature of the ground plane decreased to about 40 K. A 4 h annealing in 1-atm O 2 at 450 o C fully oxidized the buried ground plane under superconducting and insulating layers. After annealing, the critical temperature of the ground plane increased to 80 K. A sheet inductance of ~1 pH per square was measured below 40 K. We also investigated the influence of the annealing on the properties of the junctions.