A. Chantre et A. Nouailhat, PROFILE TAIL EFFECTS ON LOW-TEMPERATURE OPERATION OF SILICON BIPOLAR-TRANSISTORS, JPN J A P 1, 32(12A), 1993, pp. 5496-5502
We present a detailed investigation, in the temperature range between
340 K and 80 K, of the static properties of advanced single-polysilico
n bipolar transistors covering a wide range of base doping concentrati
ons. Special attention is paid to the temperature dependence of the in
trinsic current gain beta. We find that the rate of degradation of bet
a with temperature below about 150 K is nearly independent of the peak
or average base doping concentration. Our data do not match the conve
ntional theory of the temperature dependence of beta using available b
and-gap narrowing models for p-type silicon. We show that these, as we
ll as other recently published related results, can be understood cons
idering the importance of profile tail regions in controlling the oper
ation of bipolar transistors at low temperature.