Effect of Stress on the Excess and Hump Current in Sb-Doped Germanium Diodes

Abstract

The effects of uniaxial compression and of hydrostatic pressure on the excess and hump current in germanium tunnel diodes have been studied experimentally at 4.2°K. The diodes were formed by alloying indium doped with 3/8% gallium on (100) and (110) faces of germanium bars containing an antimony concentration of 5×10 18 cm -3 . The first order change of the current with stress was measured at fixed forward bias voltages. The experiments show that the excess current involves tunneling from the conduction band valleys to gap states on the p-type side of the junction. A large negative stress-induced current change is associated with a current component which is sometimes observed as a hump in the I–V characteristic between 0.5 and 0.65 V bias. A sharp increase of the pressure coefficient marks the onset of the ordinary injection current at 0.74 V. The effect of shear stress on the injection current was found to be zero to first order in the stress.