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Recent progress in Type-II strained layer superlattice (SLS) material systems has offered viable alternatives towards achieving large format, small-pitch, and low-cost focal plane arrays for different military and commercial applications. For focal plane array fabrication, in order to address difficulties associated with mesa-isolation etching or the complex surface treatment/ passivation process, planar structures have been considered. In this work, a comparative study on the recent progress on the planar SLS photodetector using ion-implantation for device isolation is presented. The devices presented here are nBn and pBn heterostructure InAs/InAsSb SLS photodetectors, where Zn and Si were chosen as the ion implants, respectively. The electrical and optical performance of the planar devices were compared to each other and with associated mesa-etched fabricated devices, to give a deeper view of the device performance. [ABSTRACT FROM AUTHOR]

The pandemic has posed an intense threat to the mental health of younger adults. Despite significant efforts in studying various aspects of COVID-19, there is a dearth of evidence on how negative emotions are associated with behaviors. A comparison across associated factors to different negative emotions by means of a unified model is especially missing from the literature. This study was conducted by using the results of a survey conducted across 2,534 students enrolled in 7 states in the US. Various feelings such as sad, irritable, stress and guilt were analyzed in a unified model by means of seemingly unrelated regression (SUR). Questions were asked related to rationally limiting the spread of virus, and questions related to behaviors that seem to be extreme. Irrational behaviors, such as limiting exercise at home due to COVID-19 could be due to experiencing negative emotions, which distort the meaning of events for the students. That behavior, for instance, was found to be positively associated with various negative feelings. In addition, the results highlighted significant differences across emotions in terms of demographic characteristics such as gender and age, and various precautionary actions that students take, such as limiting outdoor activities or limiting social gathering. For instance, it was highlighted while avoiding a large group of people, in spite of its importance in curbing the spread of virus, is negatively associated with various negative emotions, taking a possible nonconsequential precaution of completely limiting all people outside the immediate family result in a higher level of negative emotions. Also, it was found that having a higher body mass index (BMI), self-rated worse health conditions, and limiting outdoor activities have detrimental effects on the mental health of students. [ABSTRACT FROM AUTHOR]

In this work, a mid-wavelength infrared separate absorption and multiplication avalanche photodiode (SAM-APD) with 100% cut-off wavelength of ~ 5.0 µm at 200 K grown by molecular beam epitaxy was demonstrated. The InAsSb-based SAM-APD device was designed to have electron dominated avalanche mechanism via the band structure engineered multi-quantum well structure based on AlAsSb/GaSb H-structure superlattice and InAsSb material in the multiplication region. The device exhibits a maximum multiplication gain of 29 at 200 K under -14.7 bias voltage. The maximum multiplication gain value for the MWIR SAM-APD increases from 29 at 200 K to 121 at 150 K. The electron and hole impact ionization coefficients were derived and the large difference between their value was observed. The carrier ionization ratio for the MWIR SAM-APD device was calculated to be ~ 0.097 at 200 K. [ABSTRACT FROM AUTHOR]

In this Letter, we report the demonstration of zinc ion-implantation to realize planar mid-wavelength infrared photodetectors based on type-II InAs/InAs1−xSbx superlattices. At 77 K, the photodetectors exhibit a peak responsivity of 0.68 A/W at 3.35 μm, corresponding to a quantum efficiency of 23.5% under Vb = −80 mV, without anti-reflection coating; these photodetectors have a 100% cutoff wavelength of 4.28 μm. With an R0 × A value of 1.53 × 104 Ω cm2 and a dark current density of 1.23 × 10−6 A/cm2 under an applied bias of −80 mV at 77 K, the photodetectors exhibit a specific detectivity of 9.12 × 1011 cm·Hz1/2/W. [ABSTRACT FROM AUTHOR]

We report a Zn-diffused planar mid-wavelength infrared photodetector based on type-II InAs/InAs1−xSbx superlattices. Both the superlattice growth and Zn diffusion were performed in a metal-organic chemical vapor deposition system. At 77 K, the photodetector exhibits a peak responsivity of 0.70 A/W at 3.65 μm, corresponding to a quantum efficiency of 24% at zero bias without anti-reflection coating, with a 50% cutoff wavelength of 4.28 μm. With an R0A value of 3.2 × 105 Ω cm2 and a dark current density of 9.6 × 10−8 A/cm2 under an applied bias of −20 mV at 77 K, the photodetector exhibits a specific detectivity of 2.9 × 1012 cm Hz1/2/W. At 150 K, the photodetector exhibits a dark current density of 9.1 × 10−6 A/cm2 and a quantum efficiency of 25%, resulting in a detectivity of 3.4 × 1011 cm Hz1/2/W. [ABSTRACT FROM AUTHOR]

A high operating temperature mid-wavelength infrared pBn photodetector based on the type-II InAs/InAsSb superlattice on a GaSb substrate has been demonstrated. At 150 K, the photodetector exhibits a peak responsivity of 1.48 A/W, corresponding to a quantum efficiency of 47% at −50 mV applied bias under front-side illumination, with a 50% cutoff wavelength of 4.4 µm. With an R × A of 12 783 Ω cm2 and a dark current density of 1.16 × 10−5 A/cm2 under −50 mV applied bias, the photodetector exhibits a specific detectivity of 7.1 × 1011 cm Hz1/2/W. At 300 K, the photodetector exhibits a dark current density of 0.44 A/cm2 and a quantum efficiency of 39%, resulting in a specific detectivity of 2.5 × 109 cm Hz1/2/W. [ABSTRACT FROM AUTHOR]

We report design, growth, and characterization of midwavelength infrared nBn photodetectors based on a type-II InAs/InAs1-xSbx superlattice on a GaSb substrate grown by metal-organic chemical vapor deposition. An InAs/AlAs1-ySby/InAs/InAs1-xSbx superlattice design was used as the large bandgap electron barrier in the photodetectors. At 150 K, the photodetector exhibits a peak responsivity of 1.23 A/W, corresponding to a quantum efficiency of 41% at an applied bias voltage of −100 mV under front-side illumination, with a 50% cut-off wavelength of 4.6 μm. With an R × A of 356 Ω cm2 and a dark current density of 1.6 × 10−4 A/cm2 under an applied bias of −100 mV at 150 K, the photodetector exhibits a specific detectivity of 1.4 × 1011 cm Hz1/2/W. [ABSTRACT FROM AUTHOR]

A two terminal extended short wavelength infrared heterojunction phototransistor based on type-II InAs/AlSb/GaSb on a GaSb substrate is designed, fabricated, and investigated. With the base thickness of 40 nm, the device exhibited a 100% cut-off wavelength of ∼2.3 μm at 300 K. The saturated peak responsivity value is 320.5 A/W at 300 K, under front-side illumination without any antireflection coating. A saturated optical gain of 245 at 300 K was measured. At the same temperature, the device exhibited a collector dark current density (at unity optical gain) and a DC current gain of 7.8 × 10−3 A/cm2 and 1100, respectively. The device exhibited a saturated dark current shot noise limited specific detectivity of 4.9 × 1011 cm·Hz1/2/W at 300 K which remains constant over a broad range of wavelengths and applied biases. [ABSTRACT FROM AUTHOR]

We report the growth and characterization of mid-wavelength infrared type-II InAs/InAs1−xSbx superlattice photodiodes on GaSb substrates grown by metal-organic chemical vapor deposition. At 150 K, the 50% cut-off wavelength is 5.0 μm, the dark current density is 3.3 × 10−4 A/cm2 under −20 mV bias, and the peak responsivity is 1.76 A/W corresponding to a quantum efficiency of 55% without anti-reflection coating. A specific detectivity of 1.2 × 1011 cm Hz1/2/W is achieved at 4.0 μm under −20 mV bias at 150 K. [ABSTRACT FROM AUTHOR]

InAs/GaSb/AlSb type-II superlattice-based photodetectors, with 50% cut-off wavelength of 2.1 $\mu \text{m}$ and a −3 dB cut-off frequency of 4.8 GHz, are demonstrated, for 10 $\mu \text{m}$ diameter circular mesas under 15 V applied reverse bias. A study of the cut-off frequency with applied bias and mesa size was performed to evaluate some of the limiting factors of photodetectors high frequency performance. [ABSTRACT FROM AUTHOR]

In this paper, the effect of channel width variation on performance of double lateral gate junctionless transistors in the depletion and accumulation regimes is investigated. The characteristics of the device with various channel widths is comprehensively examined through analysis of on and off state current, threshold voltage (V th), transconductance (g m) and drain conductance (g D) variation in each operating regime. The carriers’ density distribution, electric field components and mobility are investigated through 3-D numerical simulations of the device to illustrate the variation of output characteristics. The results show that as the width decreases, the off-current (IOFF) decreases significantly as a result of better electrostatic control of the lateral gates over the channel. The on-current (ION) is also decreased mainly due to the doping-dependent mobility degradation.It is also indicated that between the flat-band and fully depleted (pinch off) variation of the majority carriers is the main parameter that modifies the characteristics of the device, while the mobility variation is recognized as the basic factor in the accumulation regime. [ABSTRACT FROM AUTHOR]

Monolithic integration of antimonide (Sb)-based compound semiconductors on Si is in high demand to enrich silicon photonics by extending the detection range to longer infrared wavelengths. In this paper, we have demonstrated the damage-free transfer of large-area (1×1 cm 2) narrow-bandgap Sb-based type-II superlattice (T2SL)-based thin-film materials onto a Si substrate using a combination of wafer-bonding and chemical epilayer release techniques. An array of Sb-based T2SL-based long-wavelength infrared (LWIR) photodetectors with diameters from 100 to 400 μm has been successfully fabricated using standard "top-down" processing technique. The transferred LWIR photodetectors exhibit a cut-off wavelength of ~8.6 μm at 77 K. The dark current density of the transferred photodetectors under 200 mV applied bias at 77 K is as low as 5.7×10 -4 A/cm 2 and the R×A reaches 66.3 Ω·cm 2, exhibiting no electrical degradation compared with reference samples on GaSb native substrate. The quantum efficiency and peak responsivity at 6.75 μm (@77 K, 200 mV) are 46.2% and 2.44 A/W, respectively. The specific detectivity (D*) at 6.75 μm reaches as high as 1.6×10 11 cm·Hz1/2 /W under 200 mV bias at 77 K. Our method opens a reliable pathway to realize high performance and practical Sb-based optoelectronic devices on a Si platform. [ABSTRACT FROM AUTHOR]

We report the demonstration of high-performance long-wavelength infrared (LWIR) nBn photodetectors based on InAs/InAs1-xSbx type-II superlattices. A new saw-tooth superlattice design was used to implement the electron barrier of the photodetectors. The device exhibited a cut-off wavelength of ~10 μm at 77 K. The photodetector exhibited a peak responsivity of 2.65 A/W, corresponding to a quantum efficiency of 43%. With an R X A of 664 Ωcm2 and a dark current density of 8 X 10-5 A/cm2, under -80 mV bias voltage at 77 K, the photodetector exhibited a specific detectivity of 4.72 X 1011 cm√Hz/W and a background-limited operating temperature of 110 K. [ABSTRACT FROM AUTHOR]

This study presents the impact of gate length scaling on analog and radio frequency (RF) performance of a self- aligned multi-gate n-type InGaAs metal oxide semiconductor field effect transistor. The device is fabricated using a self-aligned method, air-bridge technology, and 8 nm thickness of the AlO oxide layer with different gate lengths. The transconductance-to-normalized drain current ratio ( g / I ) method is implemented to investigate analog parameters. Moreover, g and drain conductance ( g ) as key parameters in analog performance of the device are evaluated with g / I and gate length variation, where g and g are both showing enhancement due to scaling of the gate length. Early voltage ( V ) and intrinsic voltage gain ( A ) value presents a decreasing trend by shrinking the gate length. In addition, the results of RF measurement for cut-off and maximum oscillation frequency for devices with different gate lengths are compared. [ABSTRACT FROM AUTHOR]

The thermal treatment method was employed to prepare nickel-cobalt oxide (NiO/Co3O4) nanoparticles. This method was attempted to achieve the higher homogeneity of the final product. Specimens of nickel-cobalt oxide were characterized by various experimental techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). X-ray diffraction results showed that there was no crystallinity in the predecessor, and it still had the amorphous phase. The formations of the crystalline phases of the nickel-cobalt oxide nanoparticles started from 350-500 °C, and the final products had different crystallite sizes ranging from 11-35 nm. Furthermore, the variation of DC conductivity (σdc), impedance, tangent loss (tgδ) and dielectric constant (ε') of the calcined specimens with frequency in the range of 10²-106 Hz was investigated. σdc showed a value of 1.9 × 10-6 S/m, 1.3 × 10-6 S/m and 1.6 × 10-6 S/m for the specimens calcined at 350, 400 and 450 °C, respectively. Additionally, a decrease in tgσ values with an increase in temperature was observed. Finally, the formed nanoparticles exhibited ferromagnetic behaviors, which were confirmed by using a vibrating sample magnetometer (VSM). [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to analyse the operation of p-type side gate junctionless silicon transistor (SGJLT) in accumulation region through experimental measurements and 3-D TCAD simulation results. The variation of electric field components, carrier’s concentration and valence band edge energy towards the accumulation region is explored with the aim of finding the origin of SGJLT performance in the accumulation operational condition.Design/methodology/approach The device is fabricated by atomic force microscopy nanolithography on silicon-on-insulator wafer. The output and transfer characteristics of the device are obtained using 3-D Technology Computer Aided Design (TCAD) Sentaurus software and compared with experimental measurement results. The advantages of AFM nanolithography in contact mode and Silicon on Insulator (SOI) technology were implemented to fabricate a simple structure which exhibits the behaviour of field effect transistors. The device has 200-nm channel length, 100-nm gate gap and 4 μm for the distance between the source and drain contacts. The characteristics of the fabricated device were measured using an Agilent HP4156C semiconductor parameter analyzer (SPA). A 3-D TCAD Sentaurus tool is used as the simulation platform. The Boltzmann statistics is adopted because of the low doping concentration of the channel. Hydrodynamic model is taken to be as the main transport model for all simulations, and the quantum mechanical effects are ignored. A doping dependent Masetti mobility model was also included as well as an electric field dependent model with Shockley–Read–Hall (SRH) carrier recombination/generation.Findings We have obtained that the device is a normally on state device mainly because of the lack of work functional difference between the gate and the channel. Analysis of electric field components’ variation, carrier’s concentration and valence band edge energy reveals that increasing the negative gate voltage drives the device into accumulation region; however, it is unable to increase the drain current significantly. The positive slope of the hole quasi-Fermi level in the accumulation region presents mechanism of carriers’ movement from source to drain. The influence of electric field because of drain and gate voltage on charge distribution explains a low increasing of the drain current when the device operates in accumulation regime.Originality/value The proposed side gate junctionless transistors simplify the fabrication process, because of the lack of gate oxide and physical junctions, and implement the atomic force microscopy nanolithography for fabrication process. The optimized structure with lower gap between gate and channel and narrower channel would present the output characteristics near the ideal transistors for next generation of scaled-down devices in both accumulation and depletion region. The presented findings are verified through experimental measurements and simulation results. [ABSTRACT FROM AUTHOR]

The use of nanoengineered metallic complex mediums in the monitoring of urine is investigated in this study. As to the mediums used, nanoscaled thin films comprised of (i) copper nanohelix structures of two different numbers of helical turns and (ii) columnar thin films of copper nanorods of two different slanting angles grown over planar glass surface – a dielectric medium – are taken into account. Turbadar–Kretschmann–Raether (TKR) configuration is used to couple light with the metallic nanoengineered thin films, and the absorption spectra are monitored corresponding to two different optical wavelengths. The void regions in nanoengineered metallic films are filled up with urine as the analyte, which causes to alter the constitutive properties, resulting thereby shifts in the peaks in absorption spectra. Prominent shifts in absorption peaks corresponding to nanoengineered mediums infiltrated with urine essentially confirm prudent optical sensing characteristics of the devices under consideration. [ABSTRACT FROM PUBLISHER]

This paper examines the impact of two important geometrical parameters, namely the thickness and source/drain extensions on the performance of low doped p-type double lateral gate junctionless transistors (DGJLTs). The three dimensional Technology Computer-Aided Design simulation is implemented to calculate the characteristics of the devices with different thickness and source/drain extension and based on that, the parameters such as threshold voltage, transconductance and resistance in saturation region are analyzed. In addition, simulation results provide a physical explanation for the variation of device characteristics given by the variation of geometric parameters, mainly based on investigation of the electric field components and the carries density variation. It is shown that, the variation of the carrier density is the main factor which affects the characteristics of the device when the device's thickness is varied. However, the electric field is mainly responsible for variation of the characteristics when the source/drain extension is changed. [ABSTRACT FROM AUTHOR]

The fabrication of Double gate (DG) and Single gate (SG) Junctionless silicon nanowire transistor (JLSNWT) was investigated in this research. The transistors used silicon nanowire patterned on lightly doped (105 cm-3) p-type silicon-on-insulator (SOI) wafer fabricated with an atomic force microscope (AFM) nanolithography technique. The top Si layer has a thickness of 90 nm and a resistivity (p) of 13.5-22.5 Ω cm. The modified RCA method implemented for sample preparation. The local anodic oxidation (LAO) followed by two wet etching steps, KOH etching for Si removal and HF etching for oxide removal, have implemented to reach the structures. The writing speed and applied tip voltage were held in 0.6 μm/s and 8.5 volt respectively. Scan speed was held in 1.0 |im/s. The etching processes were elaborately optimized by 30% wt. KOH + 10% vol. IPA in appropriate time, temperature and humidity. The structure is a gated resistor turned off based on a pinch-off effect principle, when essential positive gate voltage is applied and made a sufficiently large barrier in the gating region. Negative gate voltage is unable to make significant effect on drain current to drive the device into accumulation mode. [ABSTRACT FROM AUTHOR]

A multi-gate n-type In0.53Ga0.47As MOSFET is fabricated using gate-first self-aligned method and air-bridge technology. The devices with different gate lengths were fabricated with the Al2O3 oxide layer with the thickness of 8 nm. In this letter, impact of gate length variation on device parameter such as threshold voltage, high and low voltage transconductance, subthreshold swing and off current are investigated at room temperature. Scaling the gate length revealed good enhancement in all investigated parameters but the negative shift in threshold voltage was observed for shorter gate lengths. The high drain current of 1.13 A/mm and maximum extrinsic transconductance of 678 mS/mm with the field effect mobility of 364 cm2/Vs are achieved for the gate length and width of 0.2 µm and 30µm, respectively. The source/drain overlap length for the device is approximately extracted about 51 nm with the leakage current in order of 10−8 A. The results of RF measurement for cut-off and maximum oscillation frequency for devices with different gate lengths are compared. [ABSTRACT FROM AUTHOR]

In this paper, we have investigated the characteristics and transport features of junctionless lateral gate transistors via measurement and simulations. The transistor is fabricated using an atomic force microscopy (AFM) nanolithography technique on silicon-on-insulator (SOI) wafer. This work develops our previous examination of the device operation by using 3D numerical simulations to offer a better understanding of the origin of the transistor operation. We compare the experimental measurements and simulation results in the transfer characteristic and drain conductance. We also explore the behavior of the device in on and off states based on the variation of majority and minority carriers' density, electric-field components, and recombination/generation rate of carriers in the active region of the device. We show that the device is a normally on device that can force the current through a depleted region ( off state) and uses bulk conduction instead of surface conduction. We also found that due to the lateral gate design, low-doped channel, and lack of the gate oxide the electrostatic squeezing of the channel effectively forces the device into the off state, but the current improvement by accumulation of carriers is not significant. [ABSTRACT FROM AUTHOR]

In this letter, we investigate the fabrication of Silicon nanostructure patterned on lightly doped (1015 cm−3) p-type silicon-on-insulator by atomic force microscope nanolithography technique. The local anodic oxidation followed by two wet etching steps, potassium hydroxide etching for silicon removal and hydrofluoric etching for oxide removal, are implemented to reach the structures. The impact of contributing parameters in oxidation such as tip materials, applying voltage on the tip, relative humidity and exposure time are studied. The effect of the etchant concentration (10% to 30% wt) of potassium hydroxide and its mixture with isopropyl alcohol (10%vol. IPA ) at different temperatures on silicon surface are expressed. For different KOH concentrations, the effect of etching with the IPA admixture and the effect of the immersing time in the etching process on the structure are investigated. The etching processes are accurately optimized by 30%wt. KOH +10%vol. IPA in appropriate time, temperature, and humidity. [ABSTRACT FROM AUTHOR]

Monodispersed spherical CdS nanoparticles embedded into polyvinyl alcohol (PVA) films are synthesized by using an in-situ gamma-irradiation-induced method. The formation mechanism of CdS nanoparticles capped by two united cells of PVA is purposed by means of surrounding the CdS nanoparticles with OH bonds of the PVA chain. CdS nanoparticles are found to possess an unusual orthorhombic structure in monoclinic crystalline PVA. The polymer matrix affords protection from agglomeration and controls the particle size. It is found that the distribution of the prepared nanoparticles increases and a narrower size distribution is observed when the gamma radiation is varied from 10 to 50kGy. While the average size of the nanoparticles is found to be less affected by the variation of the gamma radiation doses. The size range of the synthesized nanoparticles is 14±1nm. The optical absorption spectra of synthesized CdS nanoparticles in a polymer matrix reveal the blue shift in the band gap energy with respect to CdS bulk materials owing to quantum confinement effect. The photoluminescence study of nanocomposite films shows the green emission arising from the crystalline defects. [ABSTRACT FROM AUTHOR]

Chromium-doped Alumina was synthesized via combustion technique. Nanoparticles were produced from aluminum nitrate, ammonium dichromate, and sucrose. Silver nitrate was used as catalyst. The use of sucrose (C12H22O11) as dispersion agent and ammonium dichromate both as fuel and a doping agent source are new techniques in the synthesis of Cr-doped Al2O3 nanoparticles. The heat-treated powders were characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Heat treatment of the nanoparticles was performed at temperatures of 900 °C, 1000 °C, and 1100 °C, which resulted in the formation of porous agglomerated chromium-doped alumina nanoparticles. Chromium-doped alumina with an average crystalline size of 35 nm was successfully synthesized via combustion technique with sucrose as fuel. [ABSTRACT FROM AUTHOR]

Iron-doped Al2O3 nanoparticles were prepared via an aqueous combustion synthesis technique using stoichiometric amounts of aluminum nitrate [(Al9NO3 )3 .9H2O], ferric nitrate [Fe(NO3)3.9H2O], and sucrose (C12H22O11). The heat treatment of the nanoparticles at two temperatures (900 °C and 1100 °C) formed porous agglomerated iron-doped alumina nanoparticles. The heat-treated powders were characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Characterization results showed existence of α-Al2O3 calcined at 1100 °C. In this study, iron-doped alumina particles with average crystallite size (38.94 nm) were successfully synthesized by using sucrose as dispersion agent and carbon source. Al2O3:Fe nanoparticles can be used in different fields as catalyst support and biocompatible material and for electrical applications. [ABSTRACT FROM AUTHOR]

Polyimide/SiO2 composite films were prepared from tetraethoxysilane (TEOS) and poly(amic acid) (PAA) based on aromatic diamine (4-aminophenyl sulfone) (4-APS) and aromatic dianhydride (3,3,4,4-benzophenonetetracarboxylic dianhydride) (BTDA) via a sol-gel process in N-methyl-2-pyrrolidinone (NMP). The prepared polyimide/SiO2 composite films were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). The FTIR results confirmed the synthesis of polyimide (4-APS/BTDA) and the formation of SiO2 particles in the polyimide matrix. Meanwhile, the SEM images showed that the SiO2 particles were well dispersed in the polyimide matrix. Thermal stability and kinetic parameters of the degradation processes for the prepared polyimide/SiO2 composite films were investigated using TGA in N2 atmosphere. The activation energy of the solid-state process was calculated using Flynn-Wall-Ozawa's method without the knowledge of the reaction mechanism. The results indicated that thermal stability and the values of the calculated activation energies increased with the increase of the TEOS loading and the activation energy also varied with the percentage of weight loss for all compositions. [ABSTRACT FROM AUTHOR]

We demonstrate low noise short wavelength infrared (SWIR) Sb-based type II superlattice (T2SL) avalanche photodiodes (APDs). The SWIR GaSb/(AlAsSb/GaSb) APD structure was designed based on impact ionization engineering and grown by molecular beam epitaxy on a GaSb substrate. At room temperature, the device exhibits a 50% cut-off wavelength of 1.74 µm. The device was revealed to have an electron-dominated avalanching mechanism with a gain value of 48 at room temperature. The electron and hole impact ionization coefficients were calculated and compared to give a better prospect of the performance of the device. Low excess noise, as characterized by a carrier ionization ratio of ~0.07, has been achieved. [ABSTRACT FROM AUTHOR]

In this letter, we report the demonstration of a pBn planar mid-wavelength infrared photodetectors based on type-II InAs/InAs1−xSbx superlattices, using silicon ion-implantation to isolate the devices. At 77 K the photodetectors exhibited peak responsivity of 0.76 A/W at 3.8 µm, corresponding to a quantum efficiency, without anti-reflection coating, of 21.5% under an applied bias of +40 mV with a 100% cut-off wavelength of 4.6 µm. With a dark current density of 5.21 × 10−6 A/cm2, under +40 mV applied bias and at 77 K, the photodetector exhibited a specific detectivity of 4.95 × 1011 cm·Hz1/2/W. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the effect of lateral gate design on performance of a p-type double lateral gate junctionless transistors (DGJLTs) with an air gate gap. The impact of lateral gate length, which modifies the real channel length of the device and gate gap variation down to 50 nm which have been found to be the most influential factors in the performance of the device have been comprehensively investigated. The characteristics are demonstrated and compared with a nominal DGJLTs through three-dimensional technology computer-aided design (TCAD) simulation. At constant channel geometry (thickness and width), when the lateral gate length decreases, the results show constant flatband drain current characteristics while the OFF state current (IOFF) increases significantly. On the other hand, by decreasing the air gap the subthreshold current considerably decreases while the flatband current is constant. Moreover, at a certain gate gap, the gates lose control over the channel and the device simply works as a resistor. Electric field component, carriers' density, band edge energies, and recombination rate of the carriers inside the channel in depletion and accumulation regimes are analysed to interpret the variation of output characteristics. [ABSTRACT FROM AUTHOR]

A laser ablation technique is applied for synthesis of silver nanoparticles in different concentrations of polyvinyl alcohol (PVA) aqueous solution. The ablation of high pure silver plate in the solution is carried out by a nanosecond Q-switched Nd:YAG pulsed laser. X-ray diffraction and transmission electron microscopy are implemented to explore the particles sizes. The effects of PVA concentrations on the absorbance of the silver nanoparticles are studied as well, by using a UV-vis spectrophotometer. The preparation process is carried out for deionized water as a reference sample. The comparison of the obtained results with the reference sample shows that the formation efficiency of nanoparticles in PVA is much higher and the sizes of particles are also smaller. [ABSTRACT FROM AUTHOR]