J. Phys. IV France 08 (1998) Pr3-103-Pr3-107
Electron impact-ionization effects in UHV/CVD SiGe HBT's in the temperature range of 300 to 83 KG. Niu, U. Gogineni and J.D. Cressler
Alabama Microelectronics Science and Technology Center, Electrical Engineering Department, 200 Broun Hall, Aubum University, Aubum AL 36849, U.S.A.
The electron impact-ionization rates (M-1) in SiGe HBT's are investigated using a new technique in the temperature range of 300 to 83K. In the new technique, the initial current for avalanche multiplication is explicitly controlled in the presence of Early effect and self-heating, and the low VCB limitation set by the open emitter current ICBO is removed. With cooling, M-1 increases first, and then saturates. when T < 117K. A 2.3V critical reverse CB voltage at which base current reversal occurs is observed at 83K, which is sufficiently high for today's bipolar and BiCMOS logic applications. Comparison with the silicon control devices suggests that the M-1 is not increased by the incorporation of SiGe, despite its smaller bandgap, indicating that SiGe HBT's are suitable for RF power applications.
© EDP Sciences 1998