Title

Surface Recombination Current Of Algaas/Gaas Heterojunction Bipolar-Transistors

Title - Alternative

Solid-State Electron.

Keywords

Small Collector Current; Emitter Current Gain; Interfaces; Hbts; Engineering, Electrical & Electronic; Physics, Applied; Physics, ; Condensed Matter

Abstract

Electron-hole recombination at the surface of a GaAs-related compound is more significant compared to that of Si. This leads to non-negligible emitter and base surface recombination currents in AlGaAs/GaAs heterojunction bipolar transistors (HBTs) due to considerable electron-hole recombination taking place at the surface of the emitter and base peripheries. Thus, unlike Si bipolar transistors in which surface recombination can be neglected, it is imperative to include surface recombination current when modeling the HBT base current. Based on the finite-difference approach and relevant device physics such as the Shockley-Read-Hall recombination statistics and Fermi level pinning, this paper develops a physics-based model for predicting emitter and base surface recombination currents of AlGaAs/GaAs HBTs. All components of the HBT base current calculated from the present model are compared, and their relative importance assessed. We show that base surface recombination current depends on exp(qV/2kT) whereas emitter surface recombination current follows an exp(qV/kT) dependence. Furthermore, it is suggested that the importance of base surface recombination current decreases as the emitter-base voltage increases, and vice versa for emitter surface recombination current. Emitter surface recombination current also becomes more significant as the ratio of emitter-base junction perimeter to area increases resulting from HBT dimension scaling. Our theoretical predictions compare favorably with numerical simulations and an empirical model available in the literature.

Publication Title

Solid-State Electronics

Volume

35

Issue/Number

6

Publication Date

1-1-1992

Document Type

Article

Language

English

First Page

805

Last Page

813

WOS Identifier

WOS:A1992HW65400008

ISSN

0038-1101

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