Structural evolution of low-dimensional metal oxide semiconductors under external stress

Metal oxide semiconductors(MOSs) are attractive candidates as functional parts and connections in nanodevices.Upon spatial dimensionality reduction, the ubiquitous strain encountered in physical reality may result in structural instability and thus degrade the performance of MOS. Hence, the basic insight into the structural evolutions of low-dimensional MOS is a prerequisite for extensive applications, which unfortunately remains largely unexplored. Herein, we review the recent progress regarding the mechanical deformation mechanisms in MOSs, such as CuO and ZnO nanowires(NWs). We report the phase transformation of CuO NWs resulting from oxygen vacancy migration under compressive stress and the tensile strain-induced phase transition in ZnO NWs. Moreover, the influence of electron beam irradiation on interpreting the mechanical behaviors is discussed.

Photoelectrocatalytic hydrogen peroxide production based on transition‐metal‐oxide semiconductors

As a kind of valuable chemicals,hydrogen peroxide(H2O2)has aroused growing attention in many fields.However,H2O2 production via traditional anthraquinone process suffers from challenges of large energy consumption and heavy carbon footprint.Alternatively,photoelectrocatalytic(PEC)production of H2O2 has shown great promises to make H2O2 a renewable fuel to store solar energy.Transition‐metal‐oxide(TMO)semiconductor based photoelectrocatalysts are among the most promising candidates for PEC H2O2 production.In this work,the fundamentals of H2O2 synthesis through PEC process are briefly introduced,followed by the state‐of‐the‐art of TMO semiconductor based photoelectrocatalysts for PEC production H2O2.Then,the progress on H2O2 fuel cells from on‐site PEC production is presented.Furthermore,the challenges and future perspectives of PEC H2O2 production are discussed.This review aims to provide inspiration for the PEC production of H2O2 as a renewable solar fuel.

Recent Progress on Flexible Room-Temperature Gas Sensors Based on Metal Oxide Semiconductor

With the rapid development of the Internet of Things,there is a great demand for portable gas sensors.Metal oxide semiconductors(MOS)are one of the most traditional and well-studied gas sensing materials and have been widely used to prepare various commercial gas sensors.However,it is limited by high operating temperature.The current research works are directed towards fabricating high-performance flexible room-temperature(FRT)gas sensors,which are effective in simplifying the structure of MOS-based sensors,reducing power consumption,and expanding the application of portable devices.This article presents the recent research progress of MOS-based FRT gas sensors in terms of sensing mechanism,performance,flexibility characteristics,and applications.This review comprehensively summarizes and discusses five types of MOS-based FRT gas sensors,including pristine MOS,noble metal nanoparticles modified MOS,organic polymers modified MOS,carbon-based materials(carbon nanotubes and graphene derivatives)modified MOS,and two-dimensional transition metal dichalcogenides materials modified MOS.The effect of light-illuminated to improve gas sensing performance is further discussed.Furthermore,the applications and future perspectives of FRT gas sensors are also discussed.

Effect of NO annealing on charge traps in oxide insulator and transition layer for 4H-SiC metal–oxide–semiconductor devices

The effect of nitric oxide（NO） annealing on charge traps in the oxide insulator and transition layer in n-type4H–Si C metal–oxide–semiconductor（MOS） devices has been investigated using the time-dependent bias stress（TDBS）,capacitance–voltage（C–V）,and secondary ion mass spectroscopy（SIMS）.It is revealed that two main categories of charge traps,near interface oxide traps（Nniot） and oxide traps（Not）,have different responses to the TDBS and C–V characteristics in NO-annealed and Ar-annealed samples.The Nniotare mainly responsible for the hysteresis occurring in the bidirectional C–V characteristics,which are very close to the semiconductor interface and can readily exchange charges with the inner semiconductor.However,Not is mainly responsible for the TDBS induced C–V shifts.Electrons tunneling into the Not are hardly released quickly when suffering TDBS,resulting in the problem of the threshold voltage stability.Compared with the Ar-annealed sample,Nniotcan be significantly suppressed by the NO annealing,but there is little improvement of Not.SIMS results demonstrate that the Nniotare distributed within the transition layer,which correlated with the existence of the excess silicon.During the NO annealing process,the excess Si atoms incorporate into nitrogen in the transition layer,allowing better relaxation of the interface strain and effectively reducing the width of the transition layer and the density of Nniot.

Improved interfacial and electrical properties of GaSb metal oxide semiconductor devices passivated with acidic(NH_4)_2S solution

Surface passivation with acidic （NH4）2S solution is shown to be effective in improving the interfacial and electrical properties of HfOE/GaSb metal oxide semiconductor devices. Compared with control samples, the samples treated with acidic （NH4）2S solution show great improvements in gate leakage current, frequency dispersion, border trap density, and interface trap density. These improvements are attributed to the enhancing passivation of the substrates, according to analysis from the perspective of chemical mechanism, X-ray photoelectron spectroscopy, and high-resolution cross-sectional transmission electron microscopy.

Investigation of trap states in Al_2O_3 InAlN/GaN metal–oxide–semiconductor high-electron-mobility transistors

In this paper the trapping effects in Al2O3/In0.17Al0.83N/GaN MOS-HEMT（here, HEMT stands for high electron mobility transistor） are investigated by frequency-dependent capacitance and conductance analysis. The trap states are found at both the Al2O3/In AlN and InAlN/GaN interface. Trap states in InAlN/GaN heterostructure are determined to have mixed de-trapping mechanisms, emission, and tunneling. Part of the electrons captured in the trap states are likely to tunnel into the two-dimensional electron gas（2DEG） channel under serious band bending and stronger electric field peak caused by high Al content in the In AlN barrier, which explains the opposite voltage dependence of time constant and relation between the time constant and energy of the trap states.

Metal oxide ion gated transistors based sensors

Metal oxide ion-gated transistors(MOIGTs)have garnered significant attention within the sensing domain due to their potential for achieving heightened sensitivity while consuming minimal energy across diverse scenarios.By harnessing the advantageous combination of metal oxides'high carrier mobility and facile surface customization,coupled with the potent signal amplification capabilities of ion-gated transistors,MOIGTs offer a promising avenue for discerning biomolecules,overseeing chemical reactions,p H levels,as well as facilitating gas or light determination.Over the past few decades,the MOIGT field has made remarkable strides in refining device physics,enhancing material properties,showcasing robust sensing capabilities,and broadening its application spectrum.These advancements have simultaneously unveiled new challenges and opportunities,necessitating interdisciplinary expertise to fully unlock the commercial potential of MOIGTs.In this comprehensive review,we offer a snapshot of this swiftly evolving technology,delve into its current applications,and provide insightful recommendations for future directions in the coming decade.

High-performance InAlGaN/GaN enhancement-mode MOS-HEMTs grown by pulsed metal organic chemical vapor deposition

Pulsed metal organic chemical vapor deposition was employed to grow nearly polarization matched InAlGaN/GaN heterostructures. A relatively low sheet carrier density of 1.8×10^(12)cm^(-2), together with a high electron mobility of1229.5 cm^2/V·s, was obtained for the prepared heterostructures. The surface morphology of the heterostructures was also significantly improved, i.e., with a root mean square roughness of 0.29 nm in a 2 μm×2 μm scan area. In addition to the improved properties, the enhancement-mode metal–oxide–semiconductor high electron mobility transistors(MOSHEMTs) processed on the heterostructures not only exhibited a high threshold voltage(VTH) of 3.1 V, but also demonstrated a significantly enhanced drain output current density of 669 m A/mm. These values probably represent the largest values obtained from the InAlGaN based enhancement-mode devices to the best of our knowledge. This study strongly indicates that the InAlGaN/GaN heterostructures grown by pulsed metal organic chemical vapor deposition could be promising for the applications of novel nitride-based electronic devices.

Experiment and simulation on degradation and burnout mechanisms of SiC MOSFET under heavy ion irradiation

Experiments and simulation studies on 283 MeV I ion induced single event effects of silicon carbide(SiC) metal–oxide–semiconductor field-effect transistors(MOSFETs) were carried out. When the cumulative irradiation fluence of the SiC MOSFET reached 5×10^(6)ion·cm^(-2), the drain–gate channel current increased under 200 V drain voltage, the drain–gate channel current and the drain–source channel current increased under 350 V drain voltage. The device occurred single event burnout under 800 V drain voltage, resulting in a complete loss of breakdown voltage. Combined with emission microscope, scanning electron microscope and focused ion beam analysis, the device with increased drain–gate channel current and drain–source channel current was found to have drain–gate channel current leakage point and local source metal melt, and the device with single event burnout was found to have local melting of its gate, source, epitaxial layer and substrate. Combining with Monte Carlo simulation and TCAD electrothermal simulation, it was found that the initial area of single event burnout might occur at the source–gate corner or the substrate–epitaxial interface, electric field and current density both affected the lattice temperature peak. The excessive lattice temperature during the irradiation process appeared at the local source contact, which led to the drain–source channel damage. And the excessive electric field appeared in the gate oxide layer, resulting in drain–gate channel damage.

Proton induced radiation effect of SiC MOSFET under different bias

Radiation effects of silicon carbide metal–oxide–semiconductor field-effect transistors(SiC MOSFETs)induced by 20 MeV proton under drain bias(V_(D)=800 V,V_(G)=0 V),gate bias(V_(D)=0 V,V_(G)=10 V),turn-on bias(V_(D)=0.5 V,V_(G)=4 V)and static bias(V_(D)=0 V,V_(G)=0 V)are investigated.The drain current of SiC MOSFET under turn-on bias increases linearly with the increase of proton fluence during the proton irradiation.When the cumulative proton fluence reaches 2×10^(11)p·cm^(-2),the threshold voltage of SiC MOSFETs with four bias conditions shifts to the left,and the degradation of electrical characteristics of SiC MOSFETs with gate bias is the most serious.In the deep level transient spectrum test,it is found that the defect energy level of SiC MOSFET is mainly the ON2(E_(c)-1.1 eV)defect center,and the defect concentration and defect capture cross section of SiC MOSFET with proton radiation under gate bias increase most.By comparing the degradation of SiC MOSFET under proton cumulative irradiation,equivalent 1 MeV neutron irradiation and gamma irradiation,and combining with the defect change of SiC MOSFET under gamma irradiation and the non-ionizing energy loss induced by equivalent 1 MeV neutron in SiC MOSFET,the degradation of SiC MOSFET induced by proton is mainly caused by ionizing radiation damage.The results of TCAD analysis show that the ionizing radiation damage of SiC MOSFET is affected by the intensity and direction of the electric field in the oxide layer and epitaxial layer.

An Optimal DPM Based Energy-Aware Task Scheduling for Performance Enhancement in Embedded MPSoC

Minimizing the energy consumption to increase the life span and performance of multiprocessor system on chip(MPSoC)has become an integral chip design issue for multiprocessor systems.The performance measurement of computational systems is changing with the advancement in technology.Due to shrinking and smaller chip size power densities onchip are increasing rapidly that increasing chip temperature in multi-core embedded technologies.The operating speed of the device decreases when power consumption reaches a threshold that causes a delay in complementary metal oxide semiconductor(CMOS)circuits because high on-chip temperature adversely affects the life span of the chip.In this paper an energy-aware dynamic power management technique based on energy aware earliest deadline first(EA-EDF)scheduling is proposed for improving the performance and reliability by reducing energy and power consumption in the system on chip(SOC).Dynamic power management(DPM)enables MPSOC to reduce power and energy consumption by adopting a suitable core configuration for task migration.Task migration avoids peak temperature values in the multicore system.High utilization factor(ui)on central processing unit(CPU)core consumes more energy and increases the temperature on-chip.Our technique switches the core bymigrating such task to a core that has less temperature and is in a low power state.The proposed EA-EDF scheduling technique migrates load on different cores to attain stability in temperature among multiple cores of the CPU and optimized the duration of the idle and sleep periods to enable the low-temperature core.The effectiveness of the EA-EDF approach reduces the utilization and energy consumption compared to other existing methods and works.The simulation results show the improvement in performance by optimizing 4.8%on u_(i) 9%,16%,23%and 25%at 520 MHz operating frequency as compared to other energy-aware techniques for MPSoCs when the least number of tasks is in running state and can schedule more tasks to make an energy-efficient processor by controlling and managing the energy consumption of MPSoC.

Energy-Efficient Scheduling Based on Task Migration Policy Using DPM for Homogeneous MPSoCs

Increasing the life span and efficiency of Multiprocessor System on Chip(MPSoC)by reducing power and energy utilization has become a critical chip design challenge for multiprocessor systems.With the advancement of technology,the performance management of central processing unit(CPU)is changing.Power densities and thermal effects are quickly increasing in multi-core embedded technologies due to shrinking of chip size.When energy consumption reaches a threshold that creates a delay in complementary metal oxide semiconductor(CMOS)circuits and reduces the speed by 10%–15%because excessive on-chip temperature shortens the chip’s life cycle.In this paper,we address the scheduling&energy utilization problem by introducing and evaluating an optimal energy-aware earliest deadline first scheduling(EA-EDF)based technique formultiprocessor environments with task migration that enhances the performance and efficiency in multiprocessor systemon-chip while lowering energy and power consumption.The selection of core andmigration of tasks prevents the system from reaching itsmaximumenergy utilization while effectively using the dynamic power management(DPM)policy.Increase in the execution of tasks the temperature and utilization factor(u_(i))on-chip increases that dissipate more power.The proposed approach migrates such tasks to the core that produces less heat and consumes less power by distributing the load on other cores to lower the temperature and optimizes the duration of idle and sleep times across multiple CPUs.The performance of the EA-EDF algorithm was evaluated by an extensive set of experiments,where excellent results were reported when compared to other current techniques,the efficacy of the proposed methodology reduces the power and energy consumption by 4.3%–4.7%on a utilization of 6%,36%&46%at 520&624 MHz operating frequency when particularly in comparison to other energy-aware methods for MPSoCs.Tasks are running and accurately scheduled to make an energy-efficient processor by controlling and managing the thermal effects on-chip and optimizing the energy consumption of MPSoCs.

A low-phase-noise and low-power crystal oscillator for RF tuner

A 37. 5 MHz differential complementary metal oxide semiconductor （CMOS） crystal oscillator with low power and low phase noise for the radio frequency tuner of digital radio broadcasting digital radio mondiale （DRAM） and digital audio broadcasting （DAB） systems is realized and characterized. The conventional cross-coupled n-type metal oxide semiconductor （NMOS） transistors are replaced by p-type metal oxide semiconductor （PMOS） transistors to decrease the phase noise in the core part of the crystal oscillator. A symmetry structure of the current mirror is adopted to increase the stability of direct current. The amplitude detecting circuit made up of a single- stage CMOS operational transconductance amplifier （OTA） and a simple amplitude detector is used to improve the current accuracy of the output signals. The chip is fabricated in a 0. 18- pxn CMOS process, and the total chip size is 0. 35 mm x 0. 3 mm. Under a supply voltage of 1.8 V, the measured power consumption is 3.6 mW including the output buffer for 50 testing loads. The proposed crystal oscillator exhibits a low phase noise of - 134. 7 dBc/Hz at 1-kHz offset from the center frequency of 37. 5 MHz.

Investigation of Gate Defects in Ultrathin MOS Structures Using DTRS Technique

s:A detailed description of relaxation spectroscopy technique under direct tunneling stress is given.A double peak phenomena by applied relaxation spectroscopy on ultra thin (<3nm) gate oxide is found.It suggests that two kinds of traps exist in the degradation of gate oxide.It is also observed that both the trap density and the generation/capture cross section of oxide trap and interface trap are smaller in ultra thin gate oxide (<3nm) under DT stress than those in the thicker oxide (>4nm) under FN stress,and the centroid of oxide trap is closer to anode interface than in the center of oxide.

A CMOS high-IF down-conversion mixer for WLAN 802.11a applications

A low noise, high conversion gain down-conversion mixer for WLAN 802.11a applications, which adopts the high intermediate frequency （IF） topology, is presented. The input radio frequency （RF）band, local oscillator（LO）frequency band and output IF are 5.15 to 5.35, 4.15 to 4.35 and 1 GHz, respectively. Source resistive degeneration technique and pseudo-differential Gilbert topology are used to achieve high linearity, and, current bleeding technique and LC resonant loads are used to acquire a low noise figure. In addition, the mixer adopts a common-source transistor pair cross-stacked with a source follow pair（CSSF）circuit as an output buffer to enhance the mixer＇s conversion gain but not deteriorate the other performances. The mixer is implemented in 0.18 μm RF CMOS（complementary metal oxide semiconductor transistor）technology and the chip area of the mixer including all bonding pads is 580 μm×1 185 μm. The measured results show that under a 1.8 V supply, the conversion gain is 10.1 dB; the input 1 dB compression point and the input-referred third-order intercept point are-3.5 and 5.3 dBm, respectively; the single side band （SSB）noise figure （NF）is 8.65 dB, and the core current consumption is 3.8 mA.

Simple point contact WO_3 sensor for NO_2 sensing and relevant impedance analysis

A simple and new point contact tungsten trioxide （WO3） sensor, which can be prepared by the oxidation of tungsten filaments via in-situ induction heating, likely detects low concentration （ppm level） environmental pollutants such as NO2. X-ray diffraction （XRD） and field emission scanning electron microscopy （FE-SEM） were applied to characterize the phase and the microstructure of the samples, respec-tively. It was found that the synthesized WO3 films exhibited a monoclinic phase and were composed of hierarchical microcrystals and nanocrystals. The point contact WO3 sensor （W-WO3-W） showed rectifying characteristics and an ideal sensing performance of about 110 C. A single semicircle in Nyquist plots was recorded by electrochemical impedance spectroscopy （EIS） at a relatively low temperature of 150 C but faded away above 200 C, which revealed that the sensing process was governed by a determining factor, i.e., grain boundaries at the contact site.

Semiconductor metal oxide compounds based gas sensors： A literature review

This paper gives a statistical view about important contributions and advances on semiconductor metal oxide （SMO） compounds based gas sensors developed to detect the air pollutants such as liquefied petroleum gas （LPG）, H2S, NH3, CO2, acetone, ethanol, other volatile compounds and hazardous gases. Moreover, it is revealed that the alloy/composite made up of SMO gas sensors show better gas response than their counterpart single component gas sensors, i.e., they are found to enhance the 4S characteristics namely speed, sensitivity, selectivity and stability. Improvement of such types of sensors used for detection of various air pollutants, which are reported in last two decades, is highlighted herein.

Effect of the Si-doped In_(0.49)Ga_(0.51)P barrier layer on the device performance of In_(0.4)Ga_(0.6)As MOSFETs grown on semi-insulating GaAs substrates

In0.4Ga0.6As channel metal-oxide-semiconductor field-effect transistors （MOSFETs） with and without an Si-doped In0.49Ga0.51P barrier layer grown on semi-insulating GaAs substrates have been investigated for the first time. Compared with the In0.4Ga0.6As MOSFETs without an In0.49Ga0.51P barrier layer, In0.4Ga0.6As MOSFETs with an In0.49Ga0.51P barrier layer show higher drive current, higher transconductance, lower gate leakage current, lower subthreshold swing, and higher effective channel mobility. These In0.4Ga0.6As MOSFETs （gate length 2 μm） with an In0.49Ga0.51P barrier layer exhibit a high drive current of 117 mA/mm, a high transconductance of 71.9 mS/mm, and a maximum effective channel mobility of 1266 cm2/（V·s）.

Recovery of PMOSFET NBTI under different conditions

Negative bias temperature instability（NBTI） has become a serious reliability issue, and the interface traps and oxide charges play an important role in the degradation process. In this paper, we study the recovery of NBTI systemically under different conditions in the P-type metal–oxide–semiconductor field effect transistor（PMOSFET）, explain the various recovery phenomena, and find the possible processes of the recovery.

X-ray irradiation-induced degradation in Hf_(0.5)Zr_(0.5)O_(2) fully depleted silicon-on-insulator n-type metal oxide semiconductor field-effect transistors

The n-type ultrathin fully depleted silicon-on-insulator(FDSOI) metal-oxide-semiconductor field-effect transistors(MOSFETs),with a Hf_(0.5)Zr_(0.5)O_(2) high dielectric permittivity(high-k) dielectric as gate insulator,were fabricated.The total ionizing dose effects were investigated,and an X-ray radiation dose up to 1500 krad(Si) was applied for both long-and short-channel devices.The short-channel devices(0.025-0.100 μm) exhibited less irradiation sensitivity compared with the long-channel devices(0.35-16 μm),leading to a 71% reduction in the irradiation-induced drain current growth and a 26% decrease in the shift of the threshold voltage.It was experimentally demonstrated that the OFF mode is the worst case among the three working conditions(OFF,ON and A110) for short-channel devices.Also,the determined effective electron mobility was enhanced by 38% after X-ray irradiation,attributed to the different compensations for charges triggered by radiation between the highk dielectric and buried oxide.By extracting the carrier mobility,gate length modulation,and source/drain(S/D)parasitic resistance,the degradation mechanism on X-ray irradiation was revealed.Finally,the split capacitance-voltage measurements were used to validate the analysis.