Resonant Tunneling through (Submicron) Si/SiGe Double Barrier Structures Fabricated by Selective Epitaxy

We have investigated transport of holes through Si/SiGe double barrier resonant tunneling structures (DBRTS) fabricated by selective epitaxy in windows in a SiO2 layer. The shunting of the DBRTS by poly-crystalline material is avoided by the use of an undercut profile of the window side walls. With this method asymmetric devices with diameters in the range of 500 nm-100 ¿m have been fabricated. The current-voltage characteristics of both large area and submicron devices show four resonances. These arise from tunneling through two heavy and two light hole states as follows from an analysis with the transfer matrix method.