Search

The oxygen deficiency-rich TiO 2 /oxygen deficiency-poor TiO 2 stacking structure grown by mist chemical vapor deposition method is used as resistive switching layers of resistive random access memory. Three different annealing temperatures of 500, 600, and 700oC are used to grow the oxygen deficiency-poor TiO 2. The experimental results indicate that the resistances of the oxygen deficiency-rich TiO 2 /oxygen deficiency-poor TiO 2 and the single-layer TiO 2 resistive random access memories are switchable by forming and rupturing the filament paths which are composed of oxygen deficiencies. The number of the filament paths is limited by the oxygen deficiency-poor TiO 2 layer, which improves the memory window and endurance of the resistive random access memory. The stacked structure with the oxygen deficiency-poor TiO 2 which is annealed at 600oC has the largest memory window of 7.8 × 105, endurable switching operation (>103 voltage loops), and long retention time (>104 s). In addition, the current conduction mechanism at the high resistance state of the RRAM with the stacked structure as the resistive switching layer is different from the one using the as-deposited TiO 2 as the resistive switching layer. [ABSTRACT FROM AUTHOR]

This study investigates InSnZnO thin films deposited using mist chemical vapor deposition with different nitrogen (N 2)/oxygen (O 2) ratios of carrier gases. The crystallinity and bandgap of InSnZnO are not affected by the carrier gases; however, the content of the oxygen deficiency of the InSnZnO thin films reduces when the N 2 /O 2 mixed carrier gases have higher oxygen ratio. The InSnZnO thin-film transistor (TFT) shows the highest field-effect mobility (65.04 cm2V−1s−1) when N 2 is used as the carrier gas to deposit the InSnZnO thin film. Although the field-effect mobility of the InSnZnO TFT that uses the N 2 (60 vol%)/O 2 (40 vol%) mixed carrier gas to deposit InSnZnO thin film is the lowest (47.65 cm2V−1s−1), it is still higher than those of the amorphous InGaZnO thin film transistors (∼10 cm2V−1s−1). Furthermore, the InSnZnO TFT using the N 2 (60 vol%)/O 2 (40 vol%) mixed carrier gas to deposit InSnZnO thin film exhibits the steepest subthreshold slope (102 mV/dec), the largest on/off current ratio (4.6 × 107), and the most stable electrical characteristics after the negative bias stress test for 10,800 s. [ABSTRACT FROM AUTHOR]

The p-GaN/N-Mg0.3Zn0.7O:In heterojunction photodiode is demonstrated in this study. The p-type GaN is grown using a hydride vapor phase epitaxy (HVPE) method and the n-type Mg0.3Zn0.7O:In thin film is deposited using a mist atmospheric pressure chemical vapor deposition (MAPCVD) method. The p-GaN/N-Mg0.3Zn0.7O:In photodiode shows a significant rectification ratio of $2.3 \times 10^{6}$ and high maximum responsivity of 0.93 A/W to UV-B. The significant UV-B to UV-A and UV-A to visible rejection ratios are found in the photodiode, which suggests that the p-GaN/N-Mg0.3Zn0.7O:In photodiode is capable of identifying visible light, UV-A, and UV-B. [ABSTRACT FROM AUTHOR]

This study investigates heterojunction thin-film transistors (HTFTs) with Mg $_{X}$ Zn $_{1- {X}}\text{O}$ /zinc oxide (ZnO) heterojunctions deposited using mist chemical vapor deposition (mist-CVD). The X-ray diffraction patterns indicate that the mist-CVD deposited Mg $_{X}$ Zn $_{1- {X}}\text{O}$ /ZnO heterojunctions are ${c}$ -axis oriented. Different Mg/Zn ratios (0.1/0.9, 0.2/0.8, and 0.3/0.7) and Mg $_{X}$ Zn $_{1- {X}}\text{O}$ thickness (15, 30, 45 nm) are used to form the Mg $_{X}$ Zn $_{1- {X}}\text{O}$ /ZnO heterojunctions of HTFTs. The Mg0.3Zn0.7O (15 nm)/ZnO HTFT exhibits high field-effect mobility of 165.56 cm2V−1s−1 and steep subthreshold slope (SS) of 106 mV/dec, but low ON-/OFF-current ratio and high gate leakage current. The Mg0.3Zn0.7O (45 nm)/ZnO HTFT shows the largest ON-/OFF-current ratio of $8.4\times10$ 8 and low gate leakage current of 19.4 pA (at ${V}_{G} =5$ V)/0.27 pA (at ${V}_{G} = -5$ V) but sacrifices the field-effect mobility and SS. The Mg0.3Zn0.7O (30 nm)/ZnO HTFT with the optimum electrical characteristics is used to estimate the stability. It is found that the Mg0.3Zn0.7O/ZnO HTFT is more stable than the ZnO thin-film transistor (TFT). [ABSTRACT FROM AUTHOR]

The 5-nm-thick Mg0.05Sn0.95Ox thin film deposited using mist chemical vapor deposition is used as a channel layer of the thin-film transistor (TFT). Mg0.05Sn0.95Ox improves the crystallinity, reduces the number of oxygen deficiencies, and enlarges the energy bandgap compared with SnO2. Mg0.05Sn0.95Ox-based TFT shows higher field-effect mobility (144.9 cm2V−1s−1), steeper subthreshold slope (134 mV/decade), and significant ON/OFF current ratio (>109) than the SnO2-based TFT. Owing to fewer oxygen-related defects, wide energy bandgaps, and stable Mg-O chemical bonding, the Mg0.05Sn0.95Ox-based TFT exhibits more stable electrical performance than the SnO2 TFT after negative bias illumination stress testing. These results suggest that Mg0.05Sn0.95Ox is a promising material for high electron mobility TFT applications. [ABSTRACT FROM AUTHOR]

This study investigates how ambient/carrier gases affect the material characteristics of amorphous indium–gallium–zinc oxide (a-InGaZnO) thin films deposited using the ultrasonic spray pyrolysis deposition (USPD) method. Nitrogen and air are used as the ambient/carrier gases in this study. The crystallinity, oxygen deficiency, energy bandgap, and trap level in the a-InGaZnO thin films are analyzed. The performance of the thin-film transistors (TFTs) based on a-InGaZnO with different ambient/carrier gases is investigated as well. It is found that oxygen deficiency is suppressed when air is used as the ambient/carrier gas. When nitrogen is used as the ambient/carrier gas to deposit a-InGaZnO thin film, the TFT shows higher field-effect mobility and saturation mobility. However, when the a-InGaZnO thin film is deposited with air as the ambient/carrier gas, the subthreshold swing, ON-/ OFF-current ratio, interface trap density, and stability of the TFT are improved. This study demonstrates how ambient/carrier gases in the USPD system affect the performance of a-InGaZnO TFT. [ABSTRACT FROM AUTHOR]

This study uses mist atmospheric pressure chemical vapor deposition with deposition/annealing cyclic method to grow c-axis aligned crystalline (CAAC) InGaZnO. The material characteristics of the CAAC-InGaZnO are analyzed by X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence, and an ellipsometer to determine the crystal structure, oxygen deficiency, trap energy level, and energy bandgap. The CAAC-InGaZnO thin-film transistor (TFT) shows better electrical performance than the one based on amorphous InGaZnO, including higher field-effect mobility (90.4 cm2 V−1 s−1), lower OFF-state leakage current (16 pA), steeper subthreshold swing (86 mV/dec), and higher on/off current ratio (>1010). Moreover, the negative bias illumination stress (NBIS) test is used to estimate the stability of the TFT. The threshold voltage of the present CAAC-InGaZnO TFT changes −0.4 V when the TFT is stressed for 10 000 s. [ABSTRACT FROM AUTHOR]

This article proposes an Mg0.35Zn0.65O/Al/ZnO structure, with which photodetectors (PDs) are able to identify ultraviolet (UV)-A (400–320 nm) and UV-B (320–280 nm). Both Mg0.35Zn0.65O and ZnO thin films are deposited using mist atmospheric pressure chemical vapor deposition (MAPCVD) method. At first, the material characteristics such as crystal structure, oxygen deficiency, energy bandgap, and photoluminescence (PL) of Mg0.35Zn0.65O and ZnO thin films are analyzed. The present Mg0.35Zn0.65O/Al/ZnO PD shows UV-B to UV-A rejection ratio of 15 in the spectral responsivity characteristics. Additionally, the detectivity characteristics suggest that the present Mg0.35Zn0.65O/Al/ZnO PD is able to identify UV-A and UV-B. Furthermore, the Mg0.35Zn0.65O/ZnO hetero-interface enhances the carrier mobility which further improves the response time. [ABSTRACT FROM AUTHOR]

This study demonstrates an amorphous indium–tin–zinc–oxide (a-ITZO) thin-film transistor (TFT) using an ultrasonic spray pyrolysis deposition (USPD) method. X-ray diffraction, X-ray photoelectron spectroscopy, Tauc plot, and photoluminescence spectrum are used to confirm the crystal structure, oxygen contents, energy bandgap, and the existence of oxygen deficiencies. Besides, these material characteristics are compared with a sputter-deposited ITZO film. The TFT based on the USPD-deposited ITZO shows better electrical performance than the TFT based on the sputter-deposited ITZO. In addition, the negative- /positive-bias illumination stress results indicate that the TFT based on the USPD-deposited ITZO film is more stable than the one based on the sputter-deposited ITZO. [ABSTRACT FROM AUTHOR]

This article demonstrates a Mg0.4Zn0.6O-based ultraviolet-B photodiode using ultrasonic spray pyrolysis deposition (USPD). The material characteristics of the USPD-deposited Mg0.4Zn0.6O thin film are investigated by the X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence, and ellipsometer. Schottky photodiode is fabricated by using Pt as the anode and Ti/Au as the cathode. Note that 0.84-eV Schottky barrier height is formed between Pt and Mg0.4Zn0.6O. The present Schottky barrier photodiode shows high rectification ratio of 104 and high ultraviolet-to-visible rejection ratio of 1.83 × 105. Furthermore, the specific detectivity is over 1011 Jones at ultraviolet-B region. [ABSTRACT FROM AUTHOR]

This paper presents the GaxZn1−xO (x = 0, 0.1, and 0.3)-based photodetectors (PDs) by using mist atmospheric pressure chemical vapor deposition. X-ray diffraction and X-ray photoelectron spectroscopy are used to characterize crystal orientation, chemical qualitative, and quantitative characteristics of the GaxZn1−x (x = 0, 0.1, and 0.3) thin films. The photoluminescence is used to observe the near-band-edge emission and trap energy level. Among these three PDs, the Ga0.3Zn0.7O-based PD shows the lowest dark current, smallest noise current, and shortest response time. Furthermore, the Ga0.3Zn0.7O-based PD exhibits higher UV-B to UV-A rejection ratio and higher UV-B to visible rejection ratio. It is found that the cutoff wavelength is tunable by changing Ga contents in GaxZn1−x thin films. [ABSTRACT FROM AUTHOR]

A nonvacuum thin-film deposition technology called ultrasonic spray pyrolysis deposition method is used to deposit fluorine-doped tin oxide, Al2O3, and TiO2 thin films, both of which are further applied on the anatase TiO2-based thin-film phototransistors (PTs). The material characteristics of the anatase TiO2 such as selected area electron diffraction, X-ray photoelectron spectroscopy, photoluminescence spectrum, and deep-level transient spectroscopy are investigated. The anatase TiO2-based thin-film PTs have a maximum output current of 4.56 mA/mm, subthreshold swing of 171 mV/dec, and threshold voltage of 0.7 V. The photoresponse characteristics of the anatase TiO2-based thin-film PTs at different quiescent-points are measured and investigated. It is found that the present anatase TiO2-based thin-film PTs can be operated in three different modes depending on the $\text{V}_{\text {DS}}$ and $\text{V}_{\text {GS}}$ biasing. In high-responsivity mode, the responsivity is 32.06 A/W; in high detectivity mode, the detectivity is $1.98 \times 10^{10}$ Jones; and in high ultraviolet (UV)-to-visible rejection ratio mode, the UV-to-visible rejection ratio is 1600. [ABSTRACT FROM AUTHOR]

This paper presents an MgO thin films deposited by an ultrasonic spray pyrolysis deposition method to serve as passivation and antireflection layers of the InGaN/GaN light-emitting diodes (LEDs). The electrical, electroluminescence (EL), and efficiency characteristics of the LEDs with 60-, 70-, and 80-nm MgO films are investigated. It is found that the LEDs with the MgO films have lower reverse currents and higher shunt resistance than that without an MgO film. However, there are no significant differences of the forward voltage at 350 mA and the series resistance between the LEDs with and without the MgO films. The significant differences between the LEDs with and without the MgO films are the light output power (LOP) and efficiency. The LED with 70-nm MgO film has the highest LOP of 556 mW (at 700 mA) and external quantum efficiency of 40.8% (at 30 mA). Further, the LED chips with the MgO films show better LOP and wall plug efficiency than those with the SiO2 and SiNx films. It is also found that the LED chips with MgO film as a passivation layer shows stable electrical and EL characteristics in the aging time test. [ABSTRACT FROM PUBLISHER]

Anatase and rutile TiO2-based metal–semiconductor–metal (MSM) ultraviolet photodetectors (PDs) are fabricated and investigated. The TiO2 thin films are grown by the ultrasonic spray pyrolysis deposition and the TiO2 films are annealed at 400 °C and 800 °C to form the anatase and the rutile phases. The material characteristics were measured by X-ray diffraction, Raman spectrum, X-ray photoelectron spectroscopy, and photoluminescence. The optical characteristics such as refractive index, extinction coefficient, absorption coefficient, and optical reflectance were characterized. The electrical and optoelectronic characteristics of the anatase and rutile TiO2 MSM PDs were characterized, including current-voltage, Schottky barrier height, spectral responsivity, response time, and detectivity. [ABSTRACT FROM AUTHOR]

This work uses ultrasonic spray pyrolysis deposition to grow the TiO 2 film on a Si substrate. The TiO 2 film was annealed at 800 °C for 2 h to form rutile phase. X-ray diffraction, Raman spectrum, X-ray photoelectron spectroscopy were used to characterized rutile phase TiO 2 . The optical characteristics like refractive index, extinction coefficient and absorption coefficient were measured. The rutile TiO 2 -based metal-semiconductor-metal ultraviolet photodetector was fabricated and investigated, including current-voltage characteristic, photoresponsivity, external quantum efficiency, response time, noise equivalent power, and detectivity. [ABSTRACT FROM AUTHOR]

This work uses ultrasonic spray pyrolysis deposition to grow titanium dioxide and aluminum oxide (Al2O3) films, respectively, as an active layer and an insulator layer of the metal–insulator–semiconductor–insulator–metal (MISIM) photodetector (PD). 10-, 20-, and 30-nm-thick Al2O3 films were deposited and the I – V characteristics in the dark and under illumination were measured and investigated. The dark current was suppressed to 11.6 pA for the MISIM PD with the 30-nm Al2O3. In addition, the carrier transportation mechanisms of the dark current are analyzed. The photoresponsivity of the MISIM PD with the 10-nm Al2O3 was 8.22 A/W (at 10 V), which is much higher than 0.84 A/W of the metal-semiconductor–metal PD. The noise equivalent power and detectivity of the MISIM PD with the 10-nm Al2O3 were 2.28\times 10^-10 W and 2.4\times 10^9 Jones. The PDs showed a slight degradation when the ambient temperature was up to 450 K. [ABSTRACT FROM AUTHOR]

This paper uses nonvacuum ultrasonic spray pyrolysis deposition method to grow TiO2 for ultraviolet (UV) detection. The analyses of the materials like X-ray photoelectron spectroscopy, X-ray diffraction, and photoluminescence were investigated. The 600 °C annealing temperature is the optimum condition to obtain the anatase TiO2. The metal–semiconductor–metal (MSM) photodetectors (PDs) with 3-, 5-, 7-, 10- \mu \textm finger spacing were fabricated and the performance was investigated. The PD with 10- \mu \textm finger spacing has the lowest dark current of 2.92\times 10^-11 A and the highest UV-to-visible rejection ratio ( $R_{{{{\rm UV}/{\rm VIS}}}}) of 2.1\times 10^5 at 5 V. The PD with 5- \mu \textm finger spacing has the lowest noise equivalent power of 2.57\times 10^-9 W and the highest detectivity ( D^\ast ) of 5.46\times 10^{8} cmHz ^{0.5}\text{W}^{-1}$ . The rising time and the falling time of the PD are 5 and 12 s. In addition, the TiO2-based MSM PD in this paper operated normally at 450 K; however, the performance is slightly degraded. The mechanisms causing degradation at high temperature were investigated. [ABSTRACT FROM AUTHOR]

This paper proposed Al2O3 deposition by ultrasonic spray pyrolysis (USP) method as an insulator layer for Al2O3/AlGaN/GaN metal-insulator-semiconductor ultraviolet photodetector (MIS-UV-PD) applications. The composition of USP-grown Al2O3 was confirmed by X-ray photoelectron spectroscopy. The refractive index and transmittance characteristics of USP-grown Al2O3 were also characterized. The Al2O3/AlGaN/GaN MIS-UV-PD performances with different Al2O3 thickness (30, 20, and 15 nm) were investigated. The responsivity was 1.3 \times 10^-3/7.5 \times 10^-3 /0.83 A/W, UV-to-visible rejection ratio was 2.34 \times 10^3/1.37 \times 10^4/3.18 \times 10^5 , and the detectivity was 2.78 \times 10^8/1.26 \times 10^9/1.17 \times 10^11 cmHz ^0.5 W ^-1 for the MIS-UV-PD with 30-/20-/15-nm-thick Al2O3. It was found that the performances of MIS-UV-PD with 15-nm Al2O3 as the insulator layer are much better than the MIS-UV-PD with 20- and 30-nm Al2O3. [ABSTRACT FROM AUTHOR]

This paper investigates the temperature-dependent performances of AlGaN/GaN metal-oxide-semiconductor high electron mobility transistor (MOS-HEMT). The gate dielectric layer and surface passivation layer are formed by the H2O2 oxidation technique. The gate dielectric quality is estimated by the breakdown electric field \((E_{{{\rm BD}}})\) and low-frequency noise. The capacitance-voltage \((C-V)\) hysteresis characteristics of MOS and Schottky diodes at 300/480 K are also studied. An appropriate thermal model is used to investigate the self-heating effect and calculate the effective channel temperature \((T_{{{\rm eff}}})\) . The dc performances of the present MOS-HEMT are improved at 300/480 K, as compared with a Schottky-barrier HEMT (SB-HEMT), including output current density, maximum extrinsic transconductance \((g_{{m,{\max }}})\) , gate voltage swing, gate-drain leakage current \((I_{{{\rm GD}}})\) , specific ON-resistance \((R_{\mathrm{{\scriptstyle ON}}})\) , three-terminal OFF-state breakdown voltage \(({\rm BV}_{\mathrm{{\scriptstyle OFF}}})\) , and subthreshold swing. Factors that cause \(I_{{{\rm GD}}}\) and \({\rm BV}_{\rm {{OFF}}}\) are analyzed by the temperature-dependent measurement. The passivation effect of the present MOS-HEMT is also confirmed by the surface leakage measurement. The devised MOS-HEMT demonstrates superior thermal stability to the reference SB-HEMT. The present-design is promising for high-temperature electronic applications. [ABSTRACT FROM AUTHOR]

Al0.3\rm Ga0.7\rm N/\rm AlN/\rm GaN metal-oxide-semiconductor high electron mobility transistors (HEMTs) grown on Si substrates by using ozone water oxidation method are investigated. Superior improvements of 52.2% in two-terminal gate-drain breakdown voltage (BVGD), 30.3% in drain-source current density (IDS) at VGS=0~V~(\rm IDSS0), 43.6% in maximum IDS~(IDS,\max), 34.7% in maximum extrinsic transconductance (gm,\max), and 52.7%/34.3% in unity-gain cutoff/maximum oscillation frequency (fT/f\max) are achieved as compared with a reference Schottky-gated HEMT. Thermal stability is studied by conducting temperature-dependent characterizations of devices at ambient temperatures of 300–550 K. Time-dependent electrical reliability analyses for the devices stressed in off-state (VGS=-20~V and VDS=0~V) for 0–60 h and on-state (VGS=2~V and VDS=20~V) for 0–20 h are also made to physically investigate the dominant degradation mechanisms. Excellent reliability and thermal stability at 300–550 K are achieved by the present design. [ABSTRACT FROM AUTHOR]

This paper investigates enhanced device characteristics of AlGaN/GaN metal–oxide–semiconductor high electron mobility transistor (HEMT) (MOS-HEMT) fabricated by using hydrogen peroxide (\H2\O2) oxidation technique which demonstrates the advantages of simplicity and cost effectiveness. A 13-nm-thick \Al2\O3 oxide was grown upon the surface of AlGaN barrier layer and served as the gate dielectric layer and the surface passivation layer at the same time to effectively decrease gate leakage current and prevent RF current collapse, which are the critical issues of nitride HEMTs. Enhanced device performances of dc, RF, power, and reliability of the present MOS-HEMT are comprehensively investigated as compared with a conventional Schottky-gate HEMT. [ABSTRACT FROM AUTHOR]

This brief reports, for the first time, an oxide-passivated AlGaN/GaN high electron mobility transistor by using the hydrogen peroxide (\H2\O2) treatment. Characterizations by using electron spectroscopy for chemical analysis and transmission electron microscopy have been performed to verify the formation of surface oxide on the AlGaN barrier layer. The present design has demonstrated superior improvements of 41% in the maximum drain/source current density I{DS, \max}, 39% in the drain/source saturation current density at zero gate bias IDSS0, 47% in the maximum extrinsic transconductance gm, \max, 53.2% in the two-terminal gate/drain breakdown voltage \BVGD, 36% in the cutoff frequency fT, and 20% in the maximum oscillation frequency f\max, as compared with an unpassivated conventional device. [ABSTRACT FROM AUTHOR]

How quiescent-points affect the performance of the ultrasonic spray pyrolysis deposited zinc oxide-based phototransistor is investigated in this study. It is well known that gate bias and drain bias control quiescent-points. By changing gate bias, strong accumulation, weak accumulation, weak depletion, and strong depletion in the active layer of the phototransistor are obtained. Meanwhile, by changing drain bias, either triode or saturation operation regions of the phototransistor is obtained. Therefore, total 8 different quiescent-points are investigated in this study. The material characteristics such as crystal structure, oxygen deficiency, bandgap, and trap energy levels are characterized. Moreover, the performance of the phototransistor at different quiescent-points are investigated. The present phototransistor shows four operation modes, including high responsivity, high UV-to-visible rejection ratio, fast response speed, and high specific detectivity, and each mode corresponds to a specific quiescent point. [ABSTRACT FROM AUTHOR]

Systematic designs to achieve normally-off operation and improved device performance for Al 0.26 Ga 0.74 N/AlN/GaN high electron mobility transistors (HEMTs) grown on a Si substrate are investigated in this work. The step-by-step approach includes: (1) devising a thin AlGaN/AlN composite barrier, (2) introducing fluoride ions within the active region by using CF 4 plasma treatment, (3) growing the Al 2 O 3 oxide passivation layers within gate-drain/source regions by using a cost-effective ozone water oxidization technique, and (4) integrating a metal-oxide-semiconductor gate (MOS-gate) design with high- k Al 2 O 3 gate dielectric. Devices with four different evolutionary gate structures have been compared and studied. Variations of threshold voltage ( V th ), Hooge coefficients ( α H ), maximum drain-source current density ( I DS, max ), maximum extrinsic transconductance ( g m, max ), gate-voltage swing ( GVS ) linearity, two-terminal gate-drain breakdown/turn-on voltages ( BV GD / V on ), on/off current ratio ( I on / I off ), and high-temperature characteristics up to 450 K are also investigated. [ABSTRACT FROM AUTHOR]

Comparative studies for TiO2-passivated Al0.25Ga0.75N/GaN heterostructure FETs (HFETs) and TiO2-dielectric MOS-HFETs using nonvacuum ultrasonic spray pyrolysis deposition technique are made. Optimum device performances are obtained by tuning the layer thickness of TiO2 to 20 nm. High relative permittivity ( k ) of 53.6 and thin effective oxide thickness of 1.45 nm are also obtained. Pulse-IV, Hooge coefficient ( \alpha _{H} ), Transmission Electron Microscopy, and atomic force microscope have been performed to characterize the interface, atomic composition, and surface flatness of the TiO2 oxide. Superior improvements for the present TiO2-dielectric MOS-HFET/TiO2-passivated HFETs are obtained, including 47.6%/23.8% in two-terminal gate–drain breakdown voltage (BV _{\rm GD}) , 111%/22.2% in two-terminal gate-drain turn-ON voltage ( V\mathrm{{\scriptscriptstyle ON}}) , 47.9%/39.4% in ON-state breakdown (BV DS) , 12.2%/10.2% in drain–source current density ( IDS) at VGS = 0 V ( IDSS0) , 27.2%/11.7% in maximum IDS ( IDS, max) , 3/1-order enhancement in on/off current ratio ( I\mathrm{{\scriptscriptstyle ON}} / I\mathrm{{\scriptscriptstyle OFF}}) , 58.8%/17.6% in gate-voltage swing linearity, 25.1%/13.2% in unity-gain cutoff frequency ( fT) , 40.6%/24.7% in maximum oscillation frequency ( f\max ) , and 33.8%/15.6% in power-added efficiency with respect to a Schottky-gated HFET fabricated on the identical epitaxial structure. The present MOS-HFET has also shown stable electrical performances when the ambient temperature is varied from 300 to 450 K. [ABSTRACT FROM AUTHOR]

Composite HfO2/Al2O3-dielectric In0.2Ga0.8As/Al0.24Ga0.76As metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) by using RF sputtering/ozone water oxidization, respectively, are investigated. In comparison with a conventional Schottky-gate device on the same epitaxial structure, an Al2O3 liner was chemically formed for the present MOS-HEMT to improve interfacial quality and decrease gate leakages. Moreover, a high-k HfO2 layer was further deposited on the Al2O3 liner to enhance the gate modulation capability. The present MOS-HEMT with the devised HfO2/Al2O3 dielectric stack has demonstrated excellent switching characteristics, including superior subthreshold slope (S.S.) of 70mV/dec and high drain-source current (IDS) on-off ratio of up to 6 orders. Improved direct-current (DC), radio-frequency (RF), and high-temperature device performances of the present design are also comprehensively studied in this work. [ABSTRACT FROM AUTHOR]