Long Duration Persistent Photocurrent in 3 nm Thin Doped Indium Oxide for Integrated Light Sensing and In-Sensor Neuromorphic Computation

Miniaturization and energy consumption by computational systems remain major challenges to address. Optoelectronics based synaptic and light sensing provide an exciting platform for neuromorphic processing and vision applications offering several advantages. It is highly desirable to achieve single-element image sensors that allow reception of information and execution of in-memory computing processes while maintaining memory for much longer durations without the need for frequent electrical or optical rehearsals. In this work, ultra-thin (<3 nm) doped indium oxide (In₂O₃) layers are engineered to demonstrate a monolithic two-terminal ultraviolet (UV) sensing and processing system with long optical state retention operating at 50 mV. This endows features of several conductance states within the persistent photocurrent window that are harnessed to show learning capabilities and significantly reduce the number of rehearsals. The atomically thin sheets are implemented as a focal plane array (FPA) for UV spectrum based proof-of-concept vision system capable of pattern recognition and memorization required for imaging and detection applications. This integrated light sensing and memory system is deployed to illustrate capabilities for real-time, in-sensor memorization, and recognition tasks. This study provides an important template to engineer miniaturized and low operating voltage neuromorphic platforms across the light spectrum based on application demand.     

Estimation of reliability of stress-strength model with non-identical component strengths

An attempt has been made in this paper to estimate the reliability of an s-out-of-k system with non-identical component strengths when component strengths follow an exponential distribution. A further assumption is made that all the components are subjected to a common random stress which also follow an exponential distribution. Bayes and maximum likelihood estimators of such system reliability are considered. A Bayes estimate is obtained by using Lindley's approximation. Comparisons are made on the basis of efficiency and Pitman nearness probability through a Monte-Carlo study.     

Analog Circuit Fault Detection Using Location of Poles

A method for detection of parametric faults occurring in linear analog circuits based on location of poles of the Circuit Under Test (CUT) is proposed. In the proposed method, the value of each component of the CUT is varied within its tolerance limit using monte carlo simulation. The upper and lower bounds of magnitude, phase angle, real part and imaginary part of all poles of the CUT are obtained. While testing, the locations of poles are obtained. If any one or more of the poles lies outside the tolerance limit then the CUT is declared faulty. The effectiveness of the proposed method is validated through two benchmark circuits like second order sallenkey band pass filter and fourth order leapfrog low pass filter.     

Effect of Colloidal Silver on Optical Transmittance Characteristics of Bulk Cadmium Zinc Telluride Crystals

Colloidal silver is observed to affect the transmittance of p-type Cd_1−y Zn _y Te (CZT) single-crystal substrate material at room temperature. The optical transmittance spectra have been analyzed in the near-infrared (NIR) and mid-infrared (MIR) regions. The transmittance characteristics of CZT showed significant reduction in absorption due to split-off valance band transitions in the NIR region and intervalence band absorption in the MIR region upon coating CZT substrates with silver paste. This reduction in absorption has been explained to be due to the compensation of the acceptor defects (native and foreign). Silver atoms incorporated from the silver coating help in compensation of these defects. A similar effect on transmittance characteristics of mercury cadmium telluride (MCT) epilayers grown on CZT substrates after coating silver paste on the CZT substrate side was also observed. An improvement in the transmittance of CZT substrates after the application of silver paste was observed. A similar improvement in transmittance is usually achieved by annealing the substrates in a Cd/Zn atmosphere. The results are explained by considering the formation of neutral complexes of acceptors (cadmium vacancies) and the interstitial silver. This study also points to the important conclusion that silver paste on CZT should be applied with caution for measurement purposes since it diffuses even at room temperature and modifies the optical characteristics.     

Generation of square and triangular wave with independently controllable frequency and amplitude using OTAs only and its application in PWM

This paper presents a self-generating square/triangular wave generator using only the CMOS Operational Transconductance Amplifiers (OTAs) and a grounded capacitor. The output frequency and amplitude of the proposed circuit can be independently and electronically adjusted. The proposed circuit validates its advantage by consuming less amount of power, which is about 71.3 µW. The theoretical aspects are authentically showcased using the PSPICE simulation results. The performance of the proposed circuit is also verified through pre layout and post layout simulation results using the 90 nm GPDK CMOS parameters. A prototype of this circuit has been made using commercially available IC CA3080 for experimental verification. Experimentation also gives the similar output as per the theoretical proposition. The designed circuit is also made applicable to perform pulse width modulation (PWM).     

引领新一代高级封装的光刻技术

在当今飞速发展的电子环境中，芯片制造商和封装技术供应商们发现传统的前段制造设备，诸如光刻步进器等，可能会实现成本高效的后段工艺流程（BEOL）器件封装。尽管高级封装市场的发展空间最初是被PCs行业的蓬勃发展带动起来的，但是现在它们已经不再是主要的增长催化因素。通信以及手持设备，如手机、PDAs（个人数字助理）、便携式游戏机以及个人通讯系统正在成为新增长阶段的推动因素。随着数字消费应用的爆炸式发展一陛能和波形系统成为必须启用高级封装（AP）技术的必要条件。在未来五年内，预计通讯芯片组、图形处理器、集成无源元件以及高速PC内存元件将成为AP技术的主要诉求。随着领先的逻辑芯片制造商们需求量的不断增大，我们共同见证了AP市场的成长过程。然而，这一细分市场的另一个转折点可能会来自高速PC内存元件对高级封装技术的诉求。