Novel epitaxial p-Si/n-Si/sub 1-y/C/sub y//p-Si heterojunction bipolar transistors

We report the fabrication and electrical characterization of the first pnp heterojunction bipolar transistors (HBTs) using a novel heterojunction system: Si/sub 1-y/C/sub y//Si (y/spl sim/0.01). Temperature dependent measurements of the collector intercept current for HBTs and Si control transistors are used to extract the Si/Si/sub 1-y/C/sub y/ bandgap difference, /spl Delta/E/sub g/ as a function of substitutional carbon fraction. These measurements are the first current-voltage extraction of the band gap reduction in Si/sub 1-y/C/sub y/, and confirm a band lineup that is more suitable for pnp HBT operation compared to Si/sub 1-x/Ge/sub x//Si. We also report what we believe are the most abrupt phosphorus doping profiles achieved using epitaxial techniques.