Search

Bio-inspired visual systems require a critical component to perceive optical stimuli and convert them into spiking signals. In this study, a compact photosensitive spiking neuron is demonstrated using a single band-modulation device called zero subthreshold swing and zero impact ionization FET (Z2-FET). This device is fully compatible with the standard CMOS process and features integrate-and-fire (IF) neural behavior. The firing threshold and spiking frequency of the Z2-FET neuron can be modulated by incident light with various intensities and wavelengths, similar to the photoresponse observed in biological neurons. TCAD simulations validate the working principle, originating from the deep depletion effect and photo-induced reduction of energy barriers. Inspired by biological neurons with adjustable spike encoding functionality, the Z2-FET neuron achieves controllable photoresponsive frequency when the input current, top-gate, and back-gate voltages are tuned. With its excellent scaling capability, low energy consumption, and tunable spiking sensitivity, the photosensitive Z2-FET neuron holds great potential in multifunctional neuromorphic applications, such as intelligent visual perception and neural computing.

The impact of the total ionizing dose (TID) on low leakage electrostatic discharge (ESD) protection devices fabricated on the 180-nm double silicon on insulator (DSOI) technology is investigated through experiments and numerical simulations. The devices under tests (DUTs) are MOS-DIO, MOS-SCR, and gate-grounded NMOSFET (GGNMOS). The transmission line pulse (TLP) measurements were carried out before and right after 60Co gamma ray irradiation. The results show that the radiation-induced charges and traps mainly located in the top buried oxide (BOX1) can lead to deterioration of ESD characteristics, such as leakage and triggering voltage. After being irradiated to a dose of 300 krad(Si), the leakage of GGNMOS increases by about three orders of magnitude, and in addition, its snapback characteristic vanishes. Radiation hardness on DSOI-based ESD devices is analyzed based on experiment and simulation results, which implies that the negative voltage on back-gate electrode can mitigate the deterioration of ESD characteristics caused due to irradiation.

With electric stressing pretreatment applied by the stress on back gate, this work demonstrates a novel gas sensing mechanism based on Au source/drain pads activated Schottky barrier-FET (SB-FET) fabricated on silicon-on-insulator (SOI) with extremely high sensitivity at room temperature, which is very different from the conventional working mechanism using gas molecular-induced channel resistance modulation for MOSFET type gas sensor. As a proof-of-concept, the interactions between ammonia (NH3) gas as the analyte and Au pads realize the SB modulation, which effectively improves the sensitivity. Besides, the SOI substrate makes the enhanced NH3 adsorption/desorption possible using the buried oxide (BOX) induced electric stress. As a result, the proposed SB-FET gas sensor shows an extremely high leakage current sensitivity up to 4 189000% for 900-ppb NH3 with a low detectable concentration down to 120 ppb.

The $\text{Z}^{{2}}$ -FET is a compact device fabricated using fully depleted silicon-on-insulator (FD-SOI) technology, and it operates with band-modulation mechanism. Due to its sharp-switching and hysteresis characteristics, the $\text{Z}^{{2}}$ -FET has shown promising applications in one-transistor dynamic random access memory (1T-DRAM) and artificial spiking neuron. In this article, we develop a novel compact $\text{Z}^{{2}}$ -FET model using an artificial neural network (ANN) approach. In light of its unique gate-controlled hysteresis behavior, our model innovatively treats the $\text{Z}^{{2}}$ -FET as a hybrid-controlled voltage source, significantly simplifying the modeling process and ensuring good accuracy in circuit simulations. To capture the transient behavior of the $\text{Z}^{{2}}$ -FET, a supplementary ANN (SA) model is established based on the unique gate charge storage effect and feedback mechanism of the $\text{Z}^{{2}}$ -FET. Using this model, the SPICE simulation results agree well with TCAD simulations, demonstrating its accuracy and reliability. Furthermore, we propose a methodology for modeling laboratory-manufactured $\text{Z}^{{2}}$ -FET devices based on measured data, which is crucial for the practical application of the developed model.

A novel implementation for electrostatic discharge (ESD) protection is demonstrated, which involves two structures named MOSFET in parallel with diode (MOS-DIO) and MOSFET in parallel with silicon-controlled rectifier (MOS-SCR). The fabricated structures exhibit enhanced robustness enabled through the double silicon-on-insulator (DSOI) technology. The implementation combines a MOSFET in the top silicon film with a diode or a silicon-controlled rectifier (SCR) located in the middle silicon layer. Transmission line pulse (TLP) experiments show that compared with the traditional single nMOS structure, both DSOI MOS-DIO and MOS-SCR exhibit superior current discharge capability with an increase in failure current of up to 39% under the same footprint. The leakage of the proposed structures is also reduced to below 0.2 pA/ $\mu \text{m}$ thanks to the double buried oxide isolation. In addition, both triggering and holding voltages can be flexibly tuned via the positioning of the two shunt devices. Technology computer-aided design (TCAD) simulations were carried out for MOS-SCR to interpret the physical mechanism and predict the performance under different device parameters, including gate length, stacked modes, and ambient temperature.