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Study of Parasitic Barriers in SiGe HBTs Due to P-n Junction Displacement and Bias Effects

Mathur, Nitish

Abstract Details

2001, MS, University of Cincinnati, Engineering : Electrical Engineering.
In this work the effects on SiGe heterojunction bipolar transistor (HBT) performance of p-n junction displacement from the SiGe/Si heterojunction at both the emitter and collector junctions have been studied using a commercial numerical device simulator ATLAS from Silvaco International. For practical devices the boron dopant in the base can outdiffuse into the emitter and collector of the SiGe HBT causing this displacement. The outdiffusion can take place during SiGe epitaxy, or during subsequent high temperature device fabrication processing. Self heating effects and electrical stressing can also contribute to this outdiffusion. The displacement of the p-n junction from the heterojunction has been found in this study to contribute to the formation of parasitic barriers in the conduction band at both the collector and emitter junctions. These barriers degrade the performance of the SiGe HBT in terms of its current gain, cutoff frequency (fT), power gain and maximum frequency of oscillation (fmax). In this research these barriers have been characterized as a function of the device structure, e.g. base width and doping, and as a function of the junction biases. Improvements to the device structure, such as the insertion of an n+ launcher layer at the collector junction, have been studied to reduce device sensitivity to outdiffusion while maintaining device performance.
Dr. Kenneth Roenker (Advisor)
164 p.

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Citations

  • Mathur, N. (2001). Study of Parasitic Barriers in SiGe HBTs Due to P-n Junction Displacement and Bias Effects [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin997446626

    APA Style (7th edition)

  • Mathur, Nitish. Study of Parasitic Barriers in SiGe HBTs Due to P-n Junction Displacement and Bias Effects. 2001. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin997446626.

    MLA Style (8th edition)

  • Mathur, Nitish. "Study of Parasitic Barriers in SiGe HBTs Due to P-n Junction Displacement and Bias Effects." Master's thesis, University of Cincinnati, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin997446626

    Chicago Manual of Style (17th edition)