Feng Guoqiang

A single-event transient induced by a pulsed laser in a silicon?germanium heterojunction bipolar transistor

A study on the single event transient (SET) induced by a pulsed laser in a silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) is presented in this work. The impacts of laser energy and collector load resistance on the SET are investigated in detail. The waveform, amplitude, and width of the SET pulse as well as collected charge are used to characterize the SET response. The experimental results are discussed in detail and it is demonstrated that the laser energy and load resistance significantly affect the SET in the SiGe HBT. Furthermore, the underlying physical mechanisms are analyzed and investigated, and a near-ideal exponential model is proposed for the first time to describe the discharge of laser-induced electrons via collector resistance to collector supply when both base-collector and collector-substrate junctions are reverse biased or weakly forward biased. Besides, it is found that an additional multi-path discharge would play an important role in the SET once the base-collector and collector-substrate junctions get strongly forward biased due to a strong transient step charge by the laser pulse.

Pulsed laser evaluation of single event transients in optocouplers

A methodology which used pulsed laser to evaluate the Single Event Transients (SETs) in the optocouplers was proposed. The SETs responses of the optocouplers were firstly investigated with the experimental simulation by pulsed laser test facility. The pulsed laser test data was compared with the ion test data to indicate the veracity and to provide insights into the SETs mechanism. The SETs characters induced by pulsed laser were qualitatively analyzed in model theory.