Impact of Ge-Profile in Base on SiGe pnp HBT’s Performance
SiGe heterojunction structure much improves the performance of PnP HBT (heterojunction bipolar transistor), which focus on the impact of Ge component distribution in the base on the current gain and characteristic frequency . The triangular distribution in the base, including zero-doping and non-zero-doping at the starting point, will form a Ge-gradient acceleration filed for the minority carriers in the base to reduce the base transport time and increase current density and working frequency. Extend Ge to the collector region to eliminate the effect of the valence band spike barrier at the collector junction, further improving the performance of the pnp HBT. By the simulations and optimizations in this paper, the and of pnp SiGe HBT improves evidently, and the results can be referenced in the design of SiGe devices and circuits.
L. Li and H. X. Liu, "Impact of Ge-Profile in Base on SiGe pnp HBT’s Performance", Advanced Materials Research, Vols. 317-319, pp. 1183-1186, 2011