Electron tunneling into Bi thin films under pressure

We have studied the pressure dependence of the tunneling resistance of tunnel junctions between 300-nm-thick Bi films and 20-nm-thick films of Al deposited at room temperature. Native Al oxide formed by oxygen glow discharge provided the tunnel barrier. The resistance was measured as a function of voltage from 0 to about 1 V. Measurements were made from room temperature to below the superconducting transition temperature of the Al film. The pressure range covered was from 0 to about 8 kbar. The resistance decreases with increasing pressure in a way easily described by simple tunneling theory. In the resistance curves we observe pressure dependence of structure, which has in the past been associated with the pressure dependence of the Bi band structure