Wei-Chou Hsu

Enhanced AlGaN/GaN MOS-HEMT Performance by Using Hydrogen Peroxide Oxidation Technique

This paper investigates enhanced device characteristics of AlGaN/GaN metal-oxide-semiconductor high electron mobility transistor (HEMT) (MOS-HEMT) fabricated by using hydrogen peroxide (H2O2) oxidation technique which demonstrates the advantages of simplicity and cost effectiveness. A 13-nm-thick Al2O3 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.

Characteristics of In/sub 0.425/Al/sub 0.575/As-InxGa/sub 1-x/As metamorphic HEMTs with pseudomorphic and symmetrically graded channels

In/sub 0.425/Al/sub 0.575/As-In/sub x/Ga/sub 1-x/As metamorphic high electron mobility transistors (MHEMTs) with two different channel designs, grown by molecular beam epitaxy (MBE) system, have been successfully investigated. Comprehensive dc and high-frequency characteristics, including the extrinsic transconductance, current driving capability, device linearity, pinch-off property, gate-voltage swing, breakdown performance, unity-gain cutoff frequency, max. oscillation frequency, output power, and power gain, etc., have been characterized and compared. In addition, complete parametric information of the small-signal device model has also been extracted and discussed for the pseudomorphic channel MHEMT (PC-MHEMT) and the V-shaped symmetrically graded channel MHEMT (SGC-MHEMT), respectively.

Novel Oxide-Passivated AlGaN/GaN HEMT by Using Hydrogen Peroxide Treatment

This brief reports, for the first time, an oxide passivated AlGaN/GaN high electron mobility transistor by using the hydrogen peroxide (H2O2) 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 IDS,max; 39% in the drain/source saturation current density at zero gate bias IDSSO, 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 fmax, as compared with an unpassivated conventional device.

High breakdown characteristic /spl delta/-doped InGaP/InGaAs/AlGaAs tunneling real-space transfer HEMT

A novel /spl delta/-doped InGaP/InGaAs/AlGaAs tunneling real-space transfer high-electron mobility transistor (TRST-HEMT) has been successfully fabricated by low-pressure metal organic chemical vapor deposition (LP-MOCVD). Three-terminal N-shaped negative differential resistance (NDR) phenomenon due to the hot electrons real-space transfer (RST) at high electric field is observed. Two-terminal gate-to-drain breakdown voltage is more than 40 V with a leakage current as low as 0.27 mA/mm. High three-terminal on-state breakdown voltage as high as 19.2 V and broad plateau of current valley as high as 15 V are achieved. These characteristics are attributed to the use of high Schottky barrier height, high bandgap of InGaP Schottky layer, /spl delta/-doping, and GaAs subspacer layers. The measured maximum peak-to-valley ratio (PVR) value is 2.7.

An Improved In0.5Ga0.5P/GaAs Double Heterostructure-Emitter Bipolar Transistor Using Emitter Edge-Thinning Technique

An improved In0.5Ga0.5P/GaAs double heterostructure-emitter bipolar transistor (DHEBT) has been fabricated by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The 100 A undoped GaAs spacers grown on both sides of the base are used to improve the recombination of p-n interface and to increase the common-emitter current gain. The emitter edge-thinning technique is used to reduce the surface recombination current and improve the current gain. A current gain of 180 with an offset voltage as low as 60 mV are achieved. Meanwhile, Gummel plot is shown to understand the composition of collector and base currents.

Performance Improvement in Tensile-Strained

This paper proposes a

hbox In_0.5hbox Al_0.5hbox As/hbox In_xhbox Ga_1-xhbox As/hbox In_0.5hbox Al_0.5hbox As

hbox In_0.5hbox Al_0.5

Metamorphic HEMT

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Enhanced resonant tunneling real-space transfer in /spl delta/-doped GaAs/InGaAs gated dual-channel transistors grown by MOCVD

hbox In_xhbox Ga_1-xhbox As

Characteristics of In0.52Al0.48As/InxGa1−xAs HEMT’s with various InxGa1−xAs channels

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