Po Wen Sze

AlGaN/GaN MOSHEMTs With Liquid-Phase-Deposited

TiO2 films deposited on GaN layers at room temperature through a simple and low-cost liquid-phase deposition (LPD) method are investigated and served as gate dielectrics in AlGaN/GaN MOSHEMTs. The electrical characteristics of the MOS structure on n-doped GaN show that the leakage current is about 1.01times10-7 A/cm2 at 1 MV/cm and that the breakdown field is more than 6.5 MV/cm. The maximum drain current density of MOSHEMTs is higher than that of conventional HEMTs, and a wider gate voltage swing can also be observed. The maximum transconductance and threshold voltage almost maintain the same characteristics, even after inserting a dielectric layer between the gate metal and the 2DEG channel by using TiO2 as a gate dielectric. The gate leakage current density is significantly improved, and the bias stress measurement shows that current collapse is much suppressed for MOSHEMTs.

\hbox{TiO}_{2}

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.

as Gate Dielectric

Barium-doped TiO2 films deposited on GaN layers at low temperature through a simple liquid phase deposition method is investigated. The use as a gate dielectric in AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors (MOSHEMTs) is also demonstrated. The electrical characteristics of the MOS structure on n-doped GaN show that the leakage current density is about 5.09 × 10-9 A/cm2 at 1 MV/cm, and the breakdown field is more than 13 MV/cm. The maximum drain current density of the AlGaN/GaN MOSHEMTs is higher than that of HEMTs, in which a wider gate voltage swing and a lower subthreshold swing (110 mV/decade) are obtained. The gate leakage current density is significantly improved, and the gate pulse measurement shows that the current collapse is more suppressed for MOSHEMTs.

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

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.

AlGaN/GaN Metal–Oxide–Semiconductor High-Electron Mobility Transistor With Liquid-Phase-Deposited Barium-Doped

The performance of n-GaN/AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) with a 20 nm thick Al 2 O 3 gate oxide deposited using the low temperature liquid phase deposition technique is demonstrated. MOSHEMTs exhibit a 23% increase in saturation drain current density, 13% higher extrinsic transconductance, and a lower gate leakage current of 3 orders of magnitude in comparison with high electron mobility transistors. The stability and the interface quality of Al 2 O 3 /n-GaN by this alternative process are discussed. The sheet carrier concentration and Hall mobility are also estimated from the channel conductance under the gate, which is comparable with those measured by the van der Pauw method before the device processing.

\hbox{TiO}_{2}

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

as a Gate Dielectric

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.

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

A new planarized trench isolation technique for GaAs devices fabrication by a liquid phase chemical-enhanced oxidation (LPCEO) method is proposed. The LPCEO-trench-isolation technique can be operated at low temperature with a simple and low-cost process. As compared with conventional mesa isolation, the LPCEO-trench-isolation can provide better planarity and isolation properties. Finally, GaAs MOSFETs fabricated with LPCEO-trench-isolation and selective oxidized gate both by the LPCEO method are demonstrated.

AlGaN/GaN Metal-Oxide-Semiconductor High Electron Mobility Transistor with Liquid Phase Deposited Al2O3 as Gate Dielectric

Abstract The gate dielectrics of Ga2O3(As2O3) of the GaAs MOSFET were prepared by a low-cost and low-temperature liquid-phase chemically enhanced oxidation method. The temperature and oxide thickness dependence of gate dielectric films on GaAs MOSFET have been investigated. The leakage current and dielectric breakdown field were both studied. Both gate leakage current density and breakdown electrical field were found to depend on the oxide thickness and operating temperature. The increasing trend in gate leakage current and the decreasing trend in breakdown electrical field were observed upon reducing oxide thickness from 30 to 12 nm and increasing operating temperature from −50°C to 200°C.

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

A process for the growth of ZnCdTe(100)GaAs heteroepitaxial films using metalorganic chemical vapor deposition (MOCVD) has been developed. It is found that substrate baking pretreatment deeply affects the characteristics of ZnxCd1 − xTe(x < 0.09) on (100)GaAs substrate (such as ZnCdTe film orientations, the Zn composition in the ZnCdTe compound alloys and the quality of ZnCdTe epilayer). We compared measurements on the same set of samples by photoreflectance (PR) and photoluminescence (PL). It was found that baking temperature (or baking time) may affect the relative contribution of each transition, resulting in a shift of the transition energy. We speculate that (100)GaAs substrates may undergo decomposition at a high baking temperature, leading to the GaAs surface change from As-stabilized surface to Ga-stabilized surface, resulting in better film PL quality and different film orientation. At higher baking temperature (or baking time), the ZnCdTe epilayer tends towards a (1 1 1) orientation and the film quality is obviously improved. Up to a temperature of around 640°C, the quality begins to decline sharply due to the destruction surface.