Han Jianwei

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.

The mechanism for SEU simulation by pulsed laser

To simulate single event effect (SEE) by pulsed laser is a new approach in ground-based simulation of SEE in recent years. In this paper the way in which picosecond pulsed laser interacts with semiconductor and the mechanism of SEE inducement are analyzed. Additionally, associated calculations are made in the case of Nd:YAG and Ti:Sapphire lasers generally used in experiments and silicon device, with comparisons made between the two lasers. In the meantime, the fundamental principle for determining laser parameters and their typical ranges of values are provided according to the results.

Synthesis of Bio-organic Molecules of Life Induced by Low Energy Ion Implantation

Gase discharge and ion implantation are respectively used in some simple water solution and solid molecular samples. The implanted samples are analysed by the 1H nuclear magnetic resonance spectra and the Fourier transform infrared spectroscopy. The results show that some new NO3− anion, NO2− anion, dimethyl ether, and ethanol are formed in the water solution samples with nitrogen, methane and carbon dioxide gas discharge. New cyano groups (-CN) and amino groups (-NH2) are formed in the irradiated solid sodium carboxylic sample with N+ ion irradiation. The experimental results present a new way to synthesize small molecules of life by low-energy ion implantation.

Simulated experiment research on SESD interference with integrated operational amplifier

Space electrostatic discharge (SESD) interference can result in soft errors to space-borne electronics and ultimately may lead to equipment or system anomalies or even whole-spacecraft failure. So far not much research work has been done on susceptibility of spacecraft equipment, especially typical electronic devices, to SESD interference. In this paper ESD generator is utilized to simulate SESD and investigate the response of LM124 OPAMP, a typical analog IC, to discharge interference. Results show that the output of LM124 may generate anomalous transient, the characteristics of which are related to device configurations, bias conditions and ESD voltage. Subjected to simulated SESD, voltage comparator only generates single polarity pulse. Voltage follower and non-inverter behave similarly. Inverter shows the least sensitivity. Sinusoidal waveform from a signal generator is injected to the input pins of LM124 to evaluate its EMI susceptibility. Analysis shows that the amplitude and duration of output pulse are strongly associated with input interference amplitude and frequency. This work has guiding significance to the intensive study of SESD effects on various typical devices, understanding the mechanism of spacecraft anomalies attributed to SESD and developing targeted protective measures.

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.