In this paper, we, for the first time, study the metal gate's work-function-fluctuation-induced variability in the 16-nm-gate bulk and silicon on insulator (SOI) fin-type field effect transistor (FinFET) devices using an experimentally calibrated 3D device simulation. According to metal's property, random nanosized grains of titanium nitride (TiN) gate are statistically positioned in the gate region to examine the associated electrostatic potential and carrier transportation characteristics, concurrently capturing fluctuations resulting from nanosized grain's random number, position and size effects. The newly advanced methodology of localised work function fluctuation simulation enables us to estimate characteristic fluctuations and to examine the nanosized grain's random effects for the 16-nm-gate bulk and SOI FinFETs with TiN/HfO 2 gate stacks with respect to the aspect ratio (AR = fin height/fin width) of two. The results of this study show that the DC characteristic fluctuation of FinFET devices strongly depends on the high and low work functions of localised nanosized metal grains. The threshold voltage (V th ) varies with the number of grain sizes and the V th 's fluctuation (σV th ) is suppressed as the grain size is minimised. σV th of SOI FinFET (about 9.7 mV) is about 1.5 times smaller than that with bulk FinFET (about 14.6 mV). Furthermore, σV th of SOI FinFET with minimal metal grain's size of 2 × 2 nm 2 can be reduced about 23%, compared with the result of bulk one.

We fabricated amorphous selenium (a-Se) photodetectors with a lateral metal-insulator-semiconductor-insulator-metal (MISIM) device structure. Thermal aluminum oxide, plasma-enhanced chemical vapor deposited silicon nitride, and thermal atomic layer deposited (ALD) aluminum oxide and hafnium oxide (ALD-HfO2) were used as the electron and hole blocking layers of the MISIM photodetectors for dark current suppression. A reduction in the dark current by three orders of magnitude can be achieved at electric fields between 10 and 30 V/μm. The effective dark current suppression is primarily ascribed to electric field lowering in the dielectric layers as a result of charge trapping in deep levels. Photogenerated carriers in the a-Se layer can be transported across the blocking layers to the Al electrodes via Fowler-Nordheim tunneling because a high electric field develops in the ultrathin dielectric layers under illumination. Since the a-Se MISIM photodetectors have a very low dark current without significant degradation in the photoresponse, the signal contrast is greatly improved. The MISIM photodetector with the ALD-HfO2 blocking layer has an optimal signal contrast more than 500 times the contrast of the photodetector without a blocking layer at 15 V/μm.

No abstract

In this study, we investigate direct current (DC)/alternating current (AC) characteristic variability induced by work function fluctuation (WKF) with respect to different nanosized metal grains and the variation of aspect ratios (ARs) of channel cross-sections on a 10 nm gate gate-all-around (GAA) nanowire (NW) metal–oxide–semiconductor field-effect transistor (MOSFET) device. The associated timing and power fluctuations of the GAA NW complementary metal–oxide–semiconductor (CMOS) circuits are further estimated and analyzed simultaneously. The experimentally validated device and circuit simulation running on a parallel computing system are intensively performed while considering the effects of WKF and various ARs to access the device’s nominal and fluctuated characteristics. To provide the best accuracy of simulation, we herein calibrate the simulation results and experimental data by adjusting the fitting parameters of the mobility model. Transfer characteristics, dynamic timing, and power consumption of the tested circuit are calculated using a mixed device–circuit simulation technique. The timing fluctuation mainly follows the trend of the variation of threshold voltage. The fluctuation terms of power consumption comprising static, short-circuit, and dynamic powers are governed by the trend that the larger the grain size, the larger the fluctuation.