Comparison of experimental and computed results on arsenic- and phosphorus-doped polysilicon emitter bipolar transistors

This paper presents a detailed comparison of the measured and computed electrical characteristics of polysilicon emitter bi-polar transistors over a wide range of processing conditions. Detailed electrical measurements are made of both the emitter resistance and the base and collector current as a function of base-emitter voltage. Devices with arsenic- and phosphorus-doped emitters are considered, as well as both with and without a deliberately grown interfacial oxide layer. The theoretical characteristics are computed using a unified model that incorporates both transport and tunneling mechanisms. It is shown that the measured emitter resistances across a wide range of processing conditions can be satisfactorily explained using a tunneling model with a single value for the electron effective barrier height (0.4 eV). Values for the modeling parameters are obtained, in some cases uniquely by measurement, and in others by fitting the experimental results. In devices with a deliberately grown interfacial oxide, the base current is suppressed to such an extent that recombination in the single-crystal emitter and in the base becomes important.