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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]

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]

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]

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]