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Highly sensitive biosensors which operate based on the utilization of random telegraph signal (RTS) noise spectroscopy might allow for the detection of diseases at the earliest stage. In this work, we provide an overview of our findings concerning RTS behavior in liquid-gated (LG) field-effect transistors (FETs). We propose different kinds of LG FET structures supported by modeling data for the extraction of characteristic RTS parameters for different carrier concentrations and operating voltages in the devices. We demonstrate the innovative aspects and opportunities of noise and fluctuations for biosensing applications. Moreover, we show that light excitation can be used to tune RTS parameters and increase the sensitivity of biosensors by at least 1.5 times. We also discuss challenges related to the utilization of RTS in different research fields, including biosensors and quantum information technology as well as ways of finding solutions to the problems. [ABSTRACT FROM AUTHOR]

A probabilistic method to remove the random telegraph signal (RTS) noise and to increase the signal level is proposed, and was verified by simulation based on measured real sensor noise. Although semi-photon-counting-level (SPCL) ultra-low noise complementary-metal-oxide-semiconductor (CMOS) image sensors (CISs) with high conversion gain pixels have emerged, they still suffer from huge RTS noise, which is inherent to the CISs. The proposed method utilizes a multi-aperture (MA) camera that is composed of multiple sets of an SPCL CIS and a moderately fast and compact imaging lens to emulate a very fast single lens. Due to the redundancy of theMAcamera, the RTS noise is removed by the maximum likelihood estimation where noise characteristics are modeled by the probability density distribution. In the proposed method, the photon shot noise is also relatively reduced because of the averaging effect, where the pixel values of all the multiple apertures are considered. An extremely low-light condition that the maximum number of electrons per aperture was the only 2e– was simulated. PSNRs of a test image for simple averaging, selective averaging (our previous method), and the proposed method were 11.92 dB, 11.61 dB, and 13.14 dB, respectively. The selective averaging, which can remove RTS noise, was worse than the simple averaging because it ignores the pixels with RTS noise and photon shot noise was less improved. The simulation results showed that the proposed method provided the best noise reduction performance. [ABSTRACT FROM AUTHOR]

Abstract: Ultra thin HfO2 high-k gate dielectric has been deposited directly on strained Si0.81Ge0.19 by atomic layer deposition process. Important electrical properties such as, interface trap density, charge trapping behavior, and low-frequency noise characteristics have been studied in detail. Grazing incidence X-ray diffraction analysis shows that the conversion from amorphous to crystalline phase start to appear in the HfO2 films when annealed between 400 and 500°C. Interface trap density was found to be in the range of 4.0–5.6×1011 eV−1 cm−2. Results of internal photoemission studies on pre-existing charge trapping for different processing conditions; without annealing and annealed in O2, N2 and mixed (O2 and N2) ambient are presented. Low-frequency noise characteristics of HfO2/Si0.81Ge0.19 stacks annealed in different gas ambient have been measured using metal–insulator–semiconductor capacitors (contact area~2×10−3 cm2). It is found that the sample annealed in N2 gas ambient shows better electrical properties in general compared to samples annealed in O2 and/or mixed (O2 and N2) gas ambient. [Copyright &y& Elsevier]

This paper presents the design and characterisation of FORTIS (4T Test Image Sensor), which is a low noise, CMOS monolithic active pixel sensor for scientific applications. The pixels present in FORTIS are based around the four transistor (4T) pixel architecture, which is already widely used in the commercial imaging community. The sensor design contains thirteen different variants of the 4T pixel architecture to investigate the effects of changing its core parameters. The variants include differences in the pixel pitch, the diode size, the in-pixel source follower, and the capacitance of the floating diffusion node (the input node of the in-pixel source follower). Processing variations have also been studied, which include varying the resistivity of the epitaxial layer and investigating the effects of a special deep p-well layer. By varying these parameters, the 4T pixel architecture can be optimised for scientific applications where detection of small amounts of charge is required. [ABSTRACT FROM PUBLISHER]

New highly sensitive direct methods for the early detection of peptides involved in Alzheimer's disease (AD) are required in order to prolong effective and healthy memory and thinking capabilities and also to stop the factors resulting in AD. In this contribution, we report the successful demonstration of a label-free approach for the detection of amyloid-beta (Aβ) peptides by highly selective aptamers immobilized onto the SiO 2 surface of the fabricated sensors. A modified single-stranded deoxyribonucleic acid (ssDNA) aptamer was specially designed and synthesized to detect the target amyloid beta-40 sequence (Aβ-40). Electrolyte–insulator–semiconductor (EIS) structures as well as silicon (Si) nanowire (NW) field-effect transistors (FETs) covered with a thin SiO 2 dielectric layer have been successfully functionalized with Aβ-40-specific aptamers and used to detect ultra-low concentrations of the target peptide. The binding of amyloid-beta peptides of different concentrations to the surface of the sensors varied in the range from 0.1 pg/ml to 10 μg/ml resulting in a change of the surface potential was registered by the fabricated devices. Moreover, we show that the single-trap phenomena observed in the novel Si two-layer (TL) NW FET structures with advanced characteristic parameters can be effectively used to increase the sensitivity of nanoscale sensors. The obtained experimental data demonstrate a highly sensitive and reliable detection of ultra-low concentrations of the Aβ-40 peptides. This opens up prospects for the development of real-time electrical biosensors for studying and understanding different stages of AD by utilizing Si TL NW FET structures fabricated on the basis of cost-efficient CMOS-compatible technology. Image 1 • High-quality two-layer Si nanowire field-effect transistor biosensors have been fabricated. • Amyloid-beta (Aβ) peptides have been successfully detected using aptamer-functionalized capacitive EIS sensors. • A novel approach for label-free detection of Aβ peptides using aptamers and single trap phenomena has been suggested. • A new strategy for Aβ peptides detection with 300% enhanced sensitivity compared to standard approaches has been developed. • The obtained results open prospects for Alzheimer's disease diagnostics. [ABSTRACT FROM AUTHOR]

Silicon two‐layer (TL) nanowire (NW) field‐effect transistors (FETs) are fabricated by applying a CMOS‐compatible top‐down approach to silicon on insulator (SOI) wafers with additionally epitaxially grown silicon layers. Transport and noise properties of fabricated structures with p‐type conductivity are studied in a wide temperature range (100–300 K). A random telegraph signal (RTS) noise as a special case of trapping‐detrapping processes is registered as a dominant noise component at room temperature. A shift of the characteristic corner (rollover) frequency of the RTS noise to lower frequencies with temperature decreasing is observed. By performing analysis of temperature‐dependent low‐frequency noise, the activation energy and hole capture cross section of a single trap responsible for the RTS noise are estimated to be (0.29 ± 0.02 eV) and (2.22 ± 0.15) ×10−18 cm2, respectively. Obtained values suggest that the trap can be attributed to a vacancy‐boron complex. At the temperature below 200 K fabricated devices demonstrate a clear generation‐recombination noise with power spectral density proportional to 1/f3/2. Such noise behavior provides the evidence of diffusion‐assisted processes in two‐layer nanowire structures. This confirms the contribution of high‐doped top silicon layer to the transistor transport properties. [ABSTRACT FROM AUTHOR]

We fabricate two-layer (TL) silicon nanowires (NW) field-effect transistors (FETs) with a liquid gate. The NW devices show advanced characteristics, which reflect reliable single-electron phenomena. A strong modulation effect of channel conductivity with effectively tuned parameters is revealed. The effect opens up prospects for applications in several research fields including bioelectronics and sensing applications. Our results shed light on the nature of single trap dynamics which parameters can be fine-tuned to enhance the sensitivity of liquid-gated TL silicon nanowire FETs.

A probabilistic method to remove the random telegraph signal (RTS) noise and to increase the signal level is proposed, and was verified by simulation based on measured real sensor noise. Although semi-photon-counting-level (SPCL) ultra-low noise complementary-metal-oxide-semiconductor (CMOS) image sensors (CISs) with high conversion gain pixels have emerged, they still suffer from huge RTS noise, which is inherent to the CISs. The proposed method utilizes a multi-aperture (MA) camera that is composed of multiple sets of an SPCL CIS and a moderately fast and compact imaging lens to emulate a very fast single lens. Due to the redundancy of the MA camera, the RTS noise is removed by the maximum likelihood estimation where noise characteristics are modeled by the probability density distribution. In the proposed method, the photon shot noise is also relatively reduced because of the averaging effect, where the pixel values of all the multiple apertures are considered. An extremely low-light condition that the maximum number of electrons per aperture was the only 2 e - was simulated. PSNRs of a test image for simple averaging, selective averaging (our previous method), and the proposed method were 11.92 dB, 11.61 dB, and 13.14 dB, respectively. The selective averaging, which can remove RTS noise, was worse than the simple averaging because it ignores the pixels with RTS noise and photon shot noise was less improved. The simulation results showed that the proposed method provided the best noise reduction performance., Competing Interests: The authors declare no conflict of interest.