Kuan Wei Lee

AlGaN/GaN Metal Oxide Semiconductor Heterostructure Field-Effect Transistor Based on a Liquid Phase Deposited Oxide

AlGaN/GaN metal oxide semiconductor heterostructure field-effect transistors (MOSHFETs) with liquid phase deposited SiO2 as the insulating gate are demonstrated. A very large gate swing voltage is applied. An AlGaN/GaN MOS heterostructure FET with saturation characteristics is observed. For a gate length of 2 µm in a 5 µm channel opening with a gate width of 100 µm, MOSHFET with transconductance and maximum drain current of 78 mS/mm and 720 mA/mm, respectively, is achieved.

InGaP/InGaAs metal-oxide-semiconductor pseudomorphic high-electron-mobility transistor with a liquid-phase-oxidized InGaP as gate dielectric

An InGaP/InGaAs metal-oxide-semiconductor pseudomorphic high-electron-mobility transistor (MOS-PHEMT) with a thin InGaP oxide layer as the gate dielectric is demonstrated. The MOS-PHEMT not only has the advantages of the MOS structure but also has the high-density, high-mobility 2DEG channel. The MOS-PHEMTs have larger gate swing voltages, lower gate leakage currents, and higher breakdown voltages than their counterpart PHEMTs have. Thus, the proposed MOS-PHEMT may be promising in power device applications.

Liquid phase chemical enhanced oxidation on AlGaAs and its application

A new method named the liquid phase chemical enhanced oxidation (LPCEO) technique has been proposed for the oxidation of aluminum gallium arsenide (AlGaAs) near room temperature. The initial stage of AlGaAs oxidation by this method has been investigated. The native oxide film composition is determined on the basis of the results of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Based on current–voltage (I–V) characteristics of the metal–oxide–semiconductor (MOS) structure, the leakage current density is approximately 5×10-9 A/cm2 at the electric field of 1 MV/cm, and the breakdown field is at least 10 MV/cm after rapid temperature annealing. In addition, the oxide film properties can be improved after thermal annealing based on capacitance–voltage (C–V) measurements. Finally, the application of the new method to the AlGaAs/InGaAs metal–oxide–semiconductor pseudomorphic high-electronic-mobility transistor (MOS-PHEMT) is demonstrated.

Improvement of Impact Ionization Effect and Subthreshold Current in InAlAs/InGaAs Metal–Oxide–Semiconductor Metamorphic HEMT With a Liquid-Phase Oxidized InAlAs as Gate Insulator

The oxidation of InAlAs and its application to InAlAs/InGaAs metal-oxide-semiconductor metamorphic high-electron mobility transistors (MOS-MHEMTs) are demonstrated in this study. After the highly selective gate recessing of InGaAs/InAlAs using citric buffer etchant, the gate dielectric is obtained directly by oxidizing the InAlAs layer in a liquid-phase solution at near room temperature. As compared to its counterpart MHEMT, the fabricated InAlAs/InGaAs MOS-MHEMT exhibits a larger tolerance to gate bias, higher breakdown voltage, lower subthreshold current, improved gate leakage current with the effectively suppressed impact ionization effect, and improved radio-frequency performance. Consequently, the liquid-phase oxidation may also be used to produce gate oxides and as an effective passivation on III-V compound semiconductor devices

Liquid phase deposited SiO2 on GaN

Abstract An efficient and low cost approach to deposit uniform silicon dioxide layers on GaN by liquid phase deposition (LPD) near room temperature are described and discussed. The process is simple. GaN wafers are immersed into a H2SiF6 and H3BO3 solution to form the silicon dioxide layers. The deposition conditions and the properties of the SiO2 films will be characterized.

Improved breakdown voltage and impact ionization in InAlAs∕InGaAs metamorphic high-electron-mobility transistor with a liquid phase oxidized InGaAs gate

The In0.52Al0.48As∕In0.53Ga0.47As metal-oxide-semiconductor metamorphic high-electron-mobility transistors (MOS-MHEMTs) with a thin InGaAs native oxide layer (∼10–15nm) are demonstrated. The gate dielectric is directly obtained by oxidizing InGaAs material in a liquid phase solution. As compared to its counterpart MHEMTs, the MOS-MHEMTs have larger gate swing voltages, higher gate-to-drain breakdown voltages, and lower gate leakage currents with the suppressed impact ionization effect due to its higher barrier height.

Liquid phase oxidation on InGaP and its application to InGaP/GaAs HBTs surface passivation

A liquid phase oxidation to grow native oxide film on InGaP near room temperature is investigated and characterized. The application as the surface passivation to improve the InGaP/GaAs heterojunction bipolar transistors (HBTs) performance is also demonstrated. In this work, the HBT devices with surface passivation by the native oxide exhibit 700% improvement in current gain at low collector current regimes by the reduction of surface recombination current, as compared to those without surface passivation. In addition, a larger breakdown voltage (23.5 V) and a lower base recombination current (10-12 A) are also obtained

InGaP/InGaAs/GaAs metal-oxide-semiconductor pseudomorphic high electron mobility transistor with a liquid phase oxidized InGaP gate

InGaP/InGaAs/GaAs metal-oxide-semiconductor pseudomorphic high electron mobility transistors (MOS-PHEMTs) are reported. The gate dielectric is formed by oxidizing InGaP material in liquid phase. As compared to its counterpart PHEMTs, it can be observed that the MOS-PHEMT has a larger gate swing voltage, a lower gate leakage current and a higher breakdown voltage. Consequentially, the studied MOS-PHEMT provides the promise for high-power applications.

Characterization of the Nanoporous Template Using Anodic Alumina Method

Porous anodic aluminum oxide (AAO) is deposited on a 5 cm × 5 cm tin-doped indium oxide (ITO)/glass substrate, and the AAO/ITO/glass structure thus formed is used to reduce the amount of unreacted Al inside the AAO template, thereby reducing the transmittance of the AAO/glass structure. The enhancement of transmittance is achieved by modulating the diameter of the pores and varying the applied bias. The proposed AAO can be used at a high applied bias (up to 120 V) to improve the uniformity of the current density. Following pore-widening treatment and posttreatment annealing, the morphologies and transmittance of the AAO/ITO/glass structure were also investigated.

Liquid phase oxidation for InGaP/GaAs HBT passivation

Native oxide films grown near room temperature by liquid phase oxidation (LPO) on p+-GaAs, n-InGaAs and n-InGaP are investigated. Their applications to heterojunction bipolar transistors (HBTs) are also demonstrated and characterized. With the LPO as surface passivation, the dc current gain β of the HBT devices increases sevenfold in low collector current regimes, and it also shows wider collector regimes from 8.3 × 10−11 A to 0.1 A. In addition, a larger breakdown voltage and lower surface recombination current can be obtained. This provides the possibility of promising implementations in low-power electronics and communication applications. Comparisons between devices with LPO passivation and those with sulfur treatment on the InGaP/GaAs HBTs are also discussed.