Novel CMOS-compatible a-Si based oscillator and threshold switch

Resistive switching devices and neuromorphic computing systems, while an attractive solution to minimize compute bottlenecks, suffer from sneak-path problem and area inefficient implementations respectively. This has prompted research in developing beyond-CMOS functional blocks that can serve as a compact single device circuit block (selector and oscillator respectively). In this work, we explore amorphous-Si based metal-semiconductor-metal (MSM) devices to serve this function. CMOS compatible Pt/a-Si/Cu stacks show negative differential resistance (NDR) that enables their operation as oscillatory elements and as non-linear threshold switches. As a first demonstration of oscillations in a-Si, we report frequency tunability from 5 kHz to 80 MHz by modulating the series ballast and by changing the source voltage. The devices show low-voltage (<; 1.2 V), low-power operation (<; 100 μW). As threshold switches, these devices show a resistance change of > 800 between ON and OFF states with a peak current density of > 0.3 MA/cm2 at 1 V. Through an analysis of the change in the snap-back time (persistence) and the peak ON-state current, we evaluate the change in the modes of operation of the device as a threshold switch and as an oscillator.