The importance of neutral base recombination in compromising the gain of Si/SiGe heterojunction bipolar transistors

Comparison of Mesa- Etched and Ion- Implanted GexSi1-x Heterojunction Bipolar Transistors

“…However, many other researchers have reported transistors with chararacteristics strongly influenced by defects of various types. For example, lower current gain than predicted has been attributed to recombination in the neutral base [4] possibly as a consequence of a high oxygen concentration [5]; recombination in the neutral base due to defects localized near the collector-base junction [6]; and recombination at the junction edge [7]. It is likely that the role of defects in a particular device is a complex function of the dopant profiles, device fabrication process, and epitaxial growth technique.…”

Base transit time of graded-base Si/SiGe HBTs considering recombination lifetime and velocity saturation

“…However, the defects such as oxygen, SiC precipitates, dislocation, and the impurities in the heavily doped SiGe(C) base decrease the minority carrier recombination lifetime (T n ), and affect the base transit time, which is a major component of the cut-off frequency. Note that the reported recombination lifetime of SiGe base was widely scattered from 10 À13 to 10 À9 s probably due to different amount of defects in the base [7][8][9]. By neglecting the effects of recombination lifetime and velocity saturation, Kroemer's model gave an integral expression of the base transit time [10].…”

Determination of bandgap narrowing and parasitic energy barriers in SiGe HBT's integrated in a bipolar technology

“…For comparison purposes, mesa transistors were also fabricated using a previously described process [19]. In this case, the extrinsic base was fabricated using a dual implant of 35 keV, 2.10 cm BF and 120 keV, 2.10 cm B into the low-doped silicon emitter to produce the structure shown in Fig.…”