Resonant tunneling diodes (RTDs) with strained i-Si/sub 0.4/Ge/sub 0.6/ potential barriers and a strained i-Si quantum well, all on a relaxed Si/sub 0.8/Ge/sub 0.2/ virtual substrate were successfully grown by ultra high vacuum compatible chemical vapor deposition and fabricated using standard Si processing methods. A large peak to valley current ratio of 2.9 and a peak current density of 4.3 kA/cm/sup 2/ at room temperature were recorded from pulsed and continuous dc current-voltage measurements, the highest reported values to date for Si/Si/sub 1-x/Ge/sub x/ RTDs. These dc figures of merit and material system render such structures suitable and highly compatible with present high speed and low power Si/Si/sub 1-x/Ge/sub x/ heterojunction field effect transistor based integrated circuits.