Showing papers in "Solid-state Electronics in 2023"
3 citations
3 citations
TL;DR: In this paper , a general slope factor expression for front and back-gate transfer characteristics of long-channel FDSOI MOSFETs in a strong gate coupling is proposed.
Abstract: In a MOSFET transistor, the subthreshold swing defines the switching efficiency, and the associated slope factor, or so-called body factor, is a critical parameter in charge-based models. However, in an advanced Fully-Depleted Silicon-On-Insulator (FDSOI) process, the slope factor is influenced by a strong back gate coupling due to a thin buried oxide (BOX). A conventional constant expression can not describe the slope factor at various back-gate voltages. Therefore, this paper proposes a general slope factor expression for front- and back-gate transfer characteristics of long-channel FDSOI MOSFETs in a strong gate coupling. The proposed expression is a continuous function of the surface potential difference between the front and back sides, which explains the slope factor behavior versus the back-gate voltage. Besides, the systematic study is presented for the front/back interface states. The proposed model is applied to evaluate the down-scaling of FDSOI technologies in terms of the gate-coupled slope factor. The scaling in the buried oxide layer degrades the front slope factor, which a thinner channel or a reverse body bias can compensate for at the cost of a higher vertical electric field. Compared to the SiO2, the application of high-κ dielectric for the buried oxide layer shows a better stand to the degraded slope factor by the interface states.
2 citations
TL;DR: In this paper , the authors investigate the performance of horizontal floating-gate field effect transistor (HFGFET) gas sensors having different FET channel width and length, and the number and length of FG fingers using both technology aided design (TCAD) device simulation and actual gas sensing measurement.
Abstract: In this study, we investigate gas sensing performance of horizontal floating-gate field-effect transistor (HFGFET) gas sensors having different FET channel width and length, and the number and length of FG fingers using both technology computer-aided design (TCAD) device simulation and actual gas sensing measurement. The HFGFET gas sensors have a control-gate (CG) and a FG, which are horizontally interdigitated. An indium oxide (In2O3) film is locally deposited between the CG and FG to be used as a sensing layer. Utilizing a simplified equivalent circuit and electrical characteristics of the HFGFET gas sensors, we define a new parameter G, which represents a magnitude of gas sensitivity. The effect of channel width and length, and the number and length of FG fingers of the HFGFET gas sensors on gas sensitivity is first investigated by TCAD device simulation, and then verified by NO2 and H2S gas sensing measurement.
1 citations
1 citations
TL;DR: In this article , the bias dependence of trap properties for GaN HEMTs with Fe-doped GaN layers was investigated using low-frequency Y-parameters measurement in the two-port network.
Abstract: The bias dependence of trap properties for GaN HEMTs with Fe-doped GaN layers was investigated using low-frequency Y-parameters measurement in the two-port network. This measurement technique can be estimated quasi-equilibrium trap properties and location by changing the combination between gate/drain current response and gate/drain input voltage with small AC signal overlapped fixed DC bias. We focused on Y22 which can be detected only in GaN traps. Activation energies for the GaN traps were estimated bias-by-bias for wide drain voltage (VDS) ranging from 2 V below the knee voltage to 15 V for the saturation region with high current at the gate voltage of 0 V (on-state condition). Fe-related GaN traps with low-frequency Y22 characteristics were identified experimentally using GaN HEMTs including GaN layers with different Fe doping concentrations. The Fe-related GaN trap signals in the imaginary part of Y22 (Im(Y22)) appeared at a peak near 200 Hz at a low VDS of 3 V under on-state conditions and moved to a higher frequency with an increase of VDS. The amplitudes of the trap peaks enhanced around VDS of 3 V. The maximum value in the amplitude of the trap peaks was large for the high-concentration Fe doping. On the other hand, the peak frequency depending on VDS had a similar trend for both the low- and high-concentration Fe doping. The activation energy for the Fe-related trap decreased for VDS up to 7 V and saturated for both Fe doping concentrations. Device simulation was performed to analyze the location in GaN HEMTs for GaN trap response and bias dependence of the activation energy. To simulate the characteristics of Im(Y22), drain current (ID) responses against AC (sine wave) input signal of VDS were calculated at the frequency corresponding to the trap peak. Because ID led VDS in phase, the trap effect is considered to change the trapped charge. From two-dimensional plots for the difference in ionized trap density, trap response regions were located under the gate edge at the drain side. Because the imaginary part of the admittance vector between ID and VDS corresponded with Im(Y22), the Fe-related traps under the gate of the drain side changed the charge condition according to the AC signal and generated the peak in Im(Y22) depending on the frequency. Furthermore, the saturation of the activation energy in the bias-dependence characteristics occurred due to decreasing the thermal conductivity at high temperatures. The temperature in GaN HEMTs at high VDS became high because of the self-heating effect in addition to the high ambient temperature. The internal temperature increase induced the trap peak frequency increase, and the activation energies were saturated.
1 citations
TL;DR: In this article , the effect of different oxygen flow rates during the radio-frequency sputter deposition of amorphous silicon-zinc-tinoxide (a-SZTO) thin film transistors (TFTs) has been studied.
Abstract: • The a-SZTO TFTs devices and their transistor parameters were investigated for different O 2 flow rates. • The post-treatment of the devices under UV irradiation for different time intervals was studied. • The stability under the UV irradiation and NBS has been significantly enhanced at a higher oxygen flow rate. • The experiment was performed on the stability enhancement under UV irradiation for different O2 flow rates for the first time. The effect of different oxygen (O 2 ) flow rates during the radio-frequency (RF) sputter deposition of amorphous silicon-zinc-tin-oxide (a-SZTO) thin film transistors (TFTs) has been studied. The threshold voltage (V th ) shifts towards the positive bias by increasing the O 2 flow rate during the deposition, which decreases the electron concentration by reducing oxygen vacancies (V Os ). The post-treatment of the devices under ultraviolet (UV) irradiation in the air atmosphere has been performed to analyze the reliability of light. The post-treatment of UV irradiation on the a-SZTO TFT for different time intervals significantly shifts the threshold voltage (V th ) from enhance- to depletion mode owing to the creation of V Os . Interestingly, we observed that UV irradiation is more effective on the parameters of V th and the current ON/OFF (I ON/OFF ) ratio for the TFTs prepared at lower O 2 flow rates. The reason may be that by introducing more oxygen flow, the de-trapping of electrons is reduced under UV irradiation due to the reduced V Os . UV irradiation does not significantly impact the field-effect mobility (µ FE ) for different O 2 flow rates. The negative bias stress measurement of the devices was performed and analyzed for different O 2 flow rates under UV irradiation treatment.
1 citations
TL;DR: In this article , a finite difference time domain (FDTD) solver for the EM wave in conjunction with a full band Monte Carlo (FBMC) model for the holes was used to simulate the generation of higher harmonics by nonlinear hole response in the p-doped silicon sample.
Abstract: THz spectroscopy with intense electromagnetic (EM) pulses offers unique avenues to study the charge carrier dynamics in semiconductors. Quantitative analysis of the experiment requires a detailed microscopic model that is based on the wave propagation within the sample and on the strongly nonparabolic dispersion relation of the valence bands. With a finite difference time domain (FDTD) solver for the EM wave in conjunction with a full band Monte Carlo (FBMC) model for the holes the generation of higher harmonics by the nonlinear hole response in the p-doped silicon sample can be simulated. Due to impurity freeze-out at the cryogenic temperature the hole density is low and the FDTD solver can be decoupled from the FBMC model by a perturbation approach. This enables the independent processing of a very large number of holes on a computer cluster with nearly 100% computational efficiency resulting in a very low level of stochastic noise, which is necessary to achieve a reasonable signal to noise ratio for the faint higher harmonics. The simulations show that at THz frequencies and cryogenic temperatures strong generation of higher harmonics is only possible, if the band structure is nonparabolic.
TL;DR: CARAT as discussed by the authors is a framework that calculates random activity (frequency and duty) aware degradation of FETs to simulate circuit aging under real operating workloads, based on actual terminal waveforms grabbed from SPICE.
Abstract: Circuit Aging Reliability Analysis Tool (CARAT), a framework that calculates random activity (frequency and duty) aware degradation of FETs to simulate circuit aging under real operating workloads is proposed. Bias Temperature Instability (BTI) and Hot Carrier Degradation (HCD) induced degradation of FETs is calculated in a cycle-by-cycle manner based on actual terminal waveforms grabbed from SPICE. Framework capability is demonstrated by using Level Shifter (LS) under random data-path activity, and Ring Oscillator (RO) under Dynamic Voltage Frequency Scaling (DVFS) conditions. The risk associated with the standard blanket approach is discussed.
TL;DR: In this article , a nonlinear photo-controlled thyristor (PCT) compatible with CMOS technology is proposed, which can achieve nonlinear changes at the same time due to the negative differential resistance effect, satisfying the requirements of an oscillatory neuron.
Abstract: With the advancement of artificial intelligence technology, volatile memristors emulating neurons have gained widespread attention in the field of neuromorphic computing. This paper proposes a volatile bipolar nonlinear photo-controlled thyristor (PCT) compatible with CMOS technology, providing a reference for the structural design of silicon-based neurons. Technology computer aided design (TCAD) simulation is used to analyze the variable-resistance mechanism and photoelectric effect of the device. The PCT fabricated based on the 0.18 μm Bipolar-CMOS-DMOS (BCD) process has two electrode ports. When a fixed amplitude bipolar periodic excitation signal is applied to the anode of the device, the output current and voltage of PCT show nonlinear changes at the same time due to the negative differential resistance effect, satisfying the fundamental requirements of an oscillatory neuron. By further coupling the photoelectric effect, the device can achieve continuous switching from high-resistance state to low-resistance state under light source driving conditions. Finally, the transient data of PCT is extracted and the hysteresis loop is fitted, which verifies the accuracy of the device theory and model simulation. Index Terms—CMOS technology, variable-resistance effect, photoelectric effect, TCAD simulation.
TL;DR: In this paper , a memristor was modulated to exhibit both synaptic effects and non-volatile switching through the use of a composite layer made of LiCoO2 and boehmite.
Abstract: In this study, a memristor was modulated to exhibit both synaptic effects and non-volatile switching through the use of a composite layer made of LiCoO2 and boehmite. At low applied bias, the memristor displayed clear synaptic behavior, functioning as an artificial neuron. At high applied bias, the memristor functioned as a binary system memory with non-volatile switching capabilities. The observed properties are thought to result from the coexistence of dual-ion mechanisms in the LiCoO2/boehmite composite layer, with the migration of Li ions and H ions controlling the synaptic effect and non-volatile switching, respectively. This study presents a promising material system for the development of novel multi-functional devices and intelligent electronics.
TL;DR: In this article , an effective way to improve the responsivity and detectivity of liquid phase epitaxy (LPE) HgCdTe avalanche focal plane array (FPA) for short-wavelength infrared (SWIR) signal detection by tuning the composition gradient was introduced.
Abstract: This work introduces an effective way to improve the responsivity and detectivity of liquid phase epitaxy (LPE) HgCdTe avalanche focal plane array (FPA) for short-wavelength infrared (SWIR) signal detection by tuning the composition gradient. It is contributed to the Hg-Cd interdiffusion at the HgCdTe/CdZnTe interface during the heat treatment. The Cd composition can be redistributed, which gives different composition (band gap) in the absorption and multiplication regions. The newly designed FPA achieves a 50% improvement in responsivity (gain) and a 30% increase in detectivity over the conventional SWIR FPA (−3 V, 80 K). The newly designed FPA also exhibits a superior performance at 130 K than the conventional FPA at 80 K.
TL;DR: In this article , a physics-based analytical DC compact model for double and single gate TMD FETs is presented by calculating the charge density inside the 2D layer which is expressed in terms of the Lambert W function that recently has become the standard in SPICE simulators.
Abstract: A physics-based analytical DC compact model for double and single gate TMD FETs is presented. The model is developed by calculating the charge density inside the 2D layer which is expressed in terms of the Lambert W function that recently has become the standard in SPICE simulators. The current is then calculated in terms of the charge densities at the drain and source ends of the channel. We validate our model against measurement data for different device structures. A superlinear current increase above certain gate voltage has been observed in some MoS2 FET devices, where we present a new mobility model to account for the observed phenomena. Despite the simplicity of the model, it shows very good agreement with the experimental data.
TL;DR: In this article , the potential benefits of metal-ferroelectric-metal-insulator-semiconductor (MFMIS) negative capacitance transistor (T) to enhance the hysteresis width (ΔVH) and reduce the minimum supply voltage (Vdd,min) of ultra low power (ULP) subthreshold Schmitt trigger (ST) at shorter gate lengths were highlighted.
Abstract: Through an analytical framework, the work showcases the potential benefits of Metal-Ferroelectric-Metal-Insulator-Semiconductor (MFMIS) negative capacitance (NC) transistor (T) to enhance the hysteresis width (ΔVH) and reduce the minimum supply voltage (Vdd,min) of ultra low power (ULP) subthreshold Schmitt trigger (ST) at shorter gate lengths. Analyzing different ST configurations i.e. 2T (both NCFET), 4T-hybrid (realized through combination of NCFETs and MOSFETs), and 6T (all NCFETs or MOSFETs), leads to the inferences that (i) an inherent negative differential resistance of NCFET can be utilized for hysteresis in 2T-ST circuit, (ii) 4T-hybrid ST is not beneficial for enhancing ΔVH due to a current mismatch between MOSFET and NCFET, and (iii) an optimized 2T-ST and 6T-ST designed with high-permittivity (κ) sidewall spacer (Si3N4) and ferroelectric layer (6 nm) can function at Vdd,min of ∼55 mV, and ∼39 mV, respectively. Results indicate towards potential benefits of realizing ULP subthreshold ST through MFMIS NCFETs without any circuit overhead.
TL;DR: In this paper , a carbon monoxide sensor has been fabricated using a NiO-based metal-organic framework (MOF)/reduced graphene oxide (rGO) composite by hydrothermal method.
Abstract: High performance gas sensors are urgently needed for the welfare of modern society. A challenge for sensors to detect analytes is its high response time. Herein, a carbon monoxide sensor has been fabricated using a NiO-based metal–organic framework(MOF)/reduced graphene oxide(rGO) composite. Synthesis of NiO-MOF and NiO-MOF/rGO were carried out by hydrothermal method. All the synthesized materials were multi parametrically tested by X-ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR), Raman spectroscopy, UV–visible spectroscopy, Atomic Force Microscopy (AFM), Field emission scanning electron microscopy (Fe-SEM), Current-Voltage characteristics (I-V), Brunauer-Emmett-Teller analysis (BET), etc. for their structural, spectroscopic, morphological, electrical, and surface properties respectively. The NiO-MOF/rGO based chemiresistive sensor fabricated on a glass substrate with a 100 µm gap through a shadow mask using an e-beam evaporator is stable up to 30 days and shows a selective response towards CO with excellent response and recovery, i.e. 30 s and 70 s respectively at 25 ppm.
TL;DR: In this article , the authors explore the stochastic switching of oxide-based memristive devices by using the Stanford model for circuit simulation and derive the D2D and cycle-to-cycle (C2C) statistical variation.
Abstract: We explore the stochastic switching of oxide-based memristive devices by using the Stanford model for circuit simulation. From measurements, the device-to-device (D2D) and cycle-to-cycle (C2C) statistical variation is extracted. In the low-resistive state (LRS) dispersion by D2D variability is dominant. In the high-resistive state (HRS) C2C dispersion becomes the main source of fluctuation. A statistical procedure for the extraction of parameters of the compact model is presented. Thereby, in a circuit simulation the typical D2D and C2C fluctuations of the current–voltage (I-V) characteristics can be emulated by extracting statistical parameters of key model parameters. The statistical distributions of the parameters are used in a Monte Carlo simulation to reproduce the I-V D2D and C2C dispersions which show a good agreement to the measured curves. The results allow the simulation of the on/off current variation for the design of memory cells or can be used to emulate the synaptic behavior of these devices in artificial neural networks realized by a crossbar array of memristors.
TL;DR: In this paper , an analytical model for the intrinsic transcapacitances in ultra-thin gate-all-around junctionless nanowire field effect transistors in the presence of confined energy states of electrons is proposed.
Abstract: In this work, we propose an analytical model for the intrinsic transcapacitances in ultra-thin gate-all-around junctionless nanowire field effect transistors in the presence of confined energy states of electrons. The validity of the developed model is confirmed from deep depletion to accumulation and from linear to saturation, based on the numerical solution of the Schrödinger equation using Technology Computer Aided Design (TCAD) simulations. This represents an important stage toward AC small signal analysis of junctionless nanowire-based circuits.
TL;DR: In this article , a simulation of tunnel current density and differential conductance using Simmon's and Brinkmann model was conducted to explore the potential of amorphous Si-Zn-Sn-O for fabricating low-resistive MTJ based spintronic devices.
Abstract: CoFeB/ Si-Zn-Sn-O /CoFeB magnetic tunnel junctions (MTJs) have been fabricated using amorphous Si-Zn-Sn-O as a low-resistive semiconducting barrier. In the low bias voltage range (up to ∼0.2 V), direct tunneling is found to be the dominant transport mechanism in MTJs. Tunneling conduction is further verified by simulation of tunnel current density and differential conductance using Simmon’s and Brinkmann model, respectively. Simulated results provided valuable insights into the barrier properties, including interfacial barrier height, thickness, and barrier asymmetry. Above the direct tunneling regime, electron transport in MTJs is governed by Pool Frenkel emission, which possibly arises due to the presence of high-density localized tail states below the conduction band of amorphous Si-Zn-Sn-O. Tunnelling magnetoresistance value of MTJs is found to be very low, which is attributed to the presence of various inelastic conduction channels. The results of this study might be useful to explore the potential of amorphous Si-Zn-Sn-O for fabricating low-resistive MTJ based spintronic devices.
TL;DR: In this paper , the reliability of silicon bipolar junction transistors and silicon germanium heterojunction bipolar transistors were studied under 80 MeV nitrogen (N6+) ions and 60Co gamma radiation in a total dose from 1 to 100Mrad at 300 K.
Abstract: The reliability of silicon bipolar junction transistors (Si BJTs) and silicon germanium heterojunction bipolar transistors (SiGe HBTs) were studied under 80 MeV nitrogen (N6+) ions and 60Co gamma radiation in a total dose from 1 to 100Mrad at 300 K. Different DC electrical parameters namely Gummel Characteristics (IB, IC–VBE), excess base current (ΔIB), current gain (hFE), and output characteristics (IC–VCE) were studied before as well as after being subjected to radiations. Both radiations caused substantial degradation in parameters such as an increase in IB, a decrease in the hFE, and a decrease in ICsat. The parametric degradation is more in Si BJT (99% degradation in hFE after ion irradiation) when compared to SiGe HBT (45% degradation in hFE). The SRIM/TRIM simulations were employed to analyze the energy loss phenomenon and ion range in device structures. Annealing studies were also conducted to study the recovery behavior of irradiated devices. The influence of linear energy transfer (LET) of radiations on damage mechanism is also discussed based on irradiation and annealing results. The results show that SiGe HBTs are more radiation hardened than Si BJTs.