A study of non-linearity effects of collector and base currents in SiGe heterojunction bipolar transistor

• Published in: ICONIP '02. Proceedings of the 9th International Conference on Neural Information Processing. Computational Intelligence for the E-Age (IEEE Cat. No.02EX575) pp. 365 - 369
• Main Authors: Rahim, A.F.A., Hashim, M.R., Rahim, A.I.A.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2002
• Subjects: Bipolar integrated circuits; Boron; Capacitive sensors; Degradation; Germanium silicon alloys; Heterojunction bipolar transistors; Physics; Silicon germanium; Solid state circuits; Temperature
• ISBN: 9780780375789; 0780375785
• DOI: 10.1109/SMELEC.2002.1217843

A material system that appears to have a tremendous advantage and compatible with Si technology is the Si-SiGe system. One problem in npn SiGe HBT is boron out-diffusion from the base. Boron dopant that out-diffuses into the emitter and collector during SiGe growth and subsequent heat treatment results in the formation of parasitic energy barriers at the emitter/base and base/collector junctions. These barriers suppress the injection of electrons from the emitter to the collector which result in reduced collector current. In this work, a study on the non-linearity effects of the collector and base currents of the SiGe HBT is performed using a high performance process and device simulator SILVACO. The understanding of these effects is very important in the fabrication of high speed devices. The characteristics shows that the more out-diffusion of boron (B) at the emitter/base and base/collector junctions, the more non-ideal the currents. The underlying explanation for these trends will be discussed.