Comparison of experiment and theory for tunneling in In-Ge: P Schottky-barrier junctions

Schottky-barrier tunnel junctions were prepared by evaporating indium on (100), vacuum-cleaved faces of phosphorus-doped germanium crystals. Measurements of dV/dI versus bias voltage were made at liquid-helium temperatures and compared to theoretical predictions for one-electron tunneling through a Schottky barrier. The theory includes the effects of the germanium ellipsoidal energy surfaces and upperconduction-band minimum (Γ₂^'). All parameters used in the theory were determined by independent measurements. Order-of-magnitude agreement between theory and experiment was found which due to the large uncertainty in the parameters used in the theory is all that can be expected. The possibility of distinguishing differences between junctions made on germanium doped with antimony, arsenic, and phosphorus are discussed. Also included is a comparison of experiment and theory for phonon-assisted tunneling.