Title

Early voltage of SiGe heterojunction bipolar transistors

Abstract

The Early voltage VA is an important parameter for the bipolar transistor (BJT). It describes the base width modulation effect in the output resistance of a BJT under the forward-active mode. Since the first paper of Early effect in 1952, numerous papers on the Early voltage for Si and SiGe bipolar transistors have been published. These papers basically treat Si bipolar behavior without including Ge content in the base. Recently, Prinz and Sturm [1] examined experimentally the trade-off between common-emitter current gain and Early voltage in SiGe heterojunction bipolar transistors using two-layer stepped SiGe bases. Zhang et al. evaluated the effect of linear Ge base grading on the Early voltage of SiGe HBTs using the analytical approach. The base recombination effect was not included in [2]. In this paper, the Early voltage of SiGe heterojunction bipolar transistors as a function of Ge grading (trapezoidal, linear, and stepped profiles) in the base is analyzed. The neutral-base recombination effect is also included. Comparison of the present model predictions against other publications and experimental data are given.

Publication Date

12-1-1997

Publication Title

Proceedings of the IEEE Hong Kong Electron Devices Meeting

Number of Pages

102-105

Document Type

Article; Proceedings Paper

Personal Identifier

scopus

Socpus ID

0031349866 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/0031349866

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