Low and High Temperature Performance of 600V 4H-SiC Epitaxial Emitter BJTs

Abstract

The paper presents a study of the different aspects of the temperature dependent performance of a 4H-SiC epi-emitter Bipolar Junction Transistor particularly the low temperature performance. Some critical device physics related factors that affect the forward active performance of the device are explored and the device behavior is modeled up to 100K. We present for the first time the experimental low-temperature (down to 100K) performance of 4H-SiC epi-emitter BJTs and the determination of the temperature beyond which the current gain starts to increase with temperature. We have also corroborated these results with 2-dimensional device simulations.

Lateral p-n-p Transistors and Complementary SiC Bipolar Technology

“…5 (a)). In agreement with previous reported results [3], in the range -40 to 300 °C the reduction in emitter efficiency of the NPN, due to the increasing ionization degree of acceptors in the base, is not yet compensated and overcome by the increase of minority carrier lifetime in the base [8], [9]. …”

“…This temperature dependence can be related to opposing phenomena affecting the gain and involving ionization degree of acceptor dopants, lifetime and mobility of minority carriers. For increasing temperature the acceptor ionization degree and the lifetime increase, while the mobility decreases [8], and its reduction is stronger at lower doping concentrations [9]. Therefore, the current gain of the PNPs is enhanced by the higher minority carriers lifetime in the base and higher emitter injection efficiency (due to the increased ionization degree of acceptor in the emitter region), but it is reduced by the lower minority carrier mobility, which in the base decreases faster than in the emitter (the doping concentration in the base of the PNPs ranges between 1×10 15 and 1×10 16 cm -3 while in the emitter it is ~ 3×10 18 cm -3 ).…”

500$^{\circ}{\rm C}$ Bipolar Integrated OR/NOR Gate in 4H-SiC

“…For higher temperature, the positive gain temperature coefficient and near to constant slope could be related to a power law dependence for the minority carrier lifetime. Compared with other available data and simulations [10], [11], our results extend the temperature range both to lower and higher temperatures and hence enable a reliable fitting. The nonmonotonous R C temperature dependence is the result of two opposing phenomena that influence the sheet resistance of the heavily doped collector layer [7] when the temperature rises: increase of dopant ionization degree and reduction of majority carrier mobility.…”

A 4H-SiC Bipolar Technology for High-Temperature Integrated Circuits

“…Although the two transistors exhibit different b, by calculating an effective activation energy for b from its constant slope versus 1000/T in the range 27-300 C, a value of approximately 40 meV is obtained for both NPNs. This behavior, already predicted by simulations [14,15], can be Fig. 7.…”