Design of n-p-n AlGaAs double-heterojunction bipolar transistors
Journal
Journal of Applied Physics
Journal Volume
62
Journal Issue
9
Pages
3976-3979
Date Issued
1987
Author(s)
Abstract
Two device structures are presented for the solution of two problems that result when an AlGaAs heterojunction bipolar transistor is used in GaAs integrated circuits. The first is the 2-kT surface recombination current problem, which seriously reduces the current gain, especially at low current level. It is found that by sandwiching a high band-gap p-type AlGaAs in the emitter-base junction interface, the 2-kT current could be substantially reduced, and the current gain displays flattened characteristics at low collector current (<1 μA). The second problem is how to reliably smooth out the potential spike at the base-collector interface which results in a serious voltage-dependent collector current in the common emitter I-V characteristics of the transistors. It is found that by adding a thin spacer layer with the same composition but the opposite type as the base layer in the base-collector junction interface, the potential spike can be easily and reproducibly suppressed.
SDGs
Type
journal article