Bo-Yi Chou

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.

A Simple Gate-Dielectric Fabrication Process for AlGaN/GaN Metal–Oxide–Semiconductor High-Electron-Mobility Transistors

This letter reports a simple processing method for fabricating metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) by using hydrogen peroxide (H₂O₂) oxidation technique. Aluminum oxide (AlO_x) was formed on the surface of the AlGaN barrier as the gate dielectric of the MOS-gate structure. By using the capacitance-voltage measurement, the dielectric constant (κ) of AlO_x was determined to be 9.2. The present MOS-HEMT has demonstrated enhanced saturation drain current density at V_GS = 0 V (I_DSS0) of 552.3 mA/mm, maximum extrinsic transconductance (g_{m, max}) of 136 mS/mm, wide gate voltage swing of 2.9 V, and two-terminal gate-drain breakdown/turn-on voltages (BV_GD/V_on) of -132.2/1.82 V.

Investigations of AlGaN/AlN/GaN MOS-HEMTs on Si Substrate by Ozone Water Oxidation Method

Al_0.3Ga_0.7N/AlN/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 (BV_GD), 30.3% in drain-source current density (I_DS) at V_GS = 0 V (I_DSS0), 43.6% in maximum I_DS (I_DS,max), 34.7% in maximum extrinsic transconductance (<i>gm</i>,max), and 52.7%/34.3% in unity-gain cutoff/maximum oscillation frequency (<i>fT</i>/<i>f</i>_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 (V_GS = -20 V and V_DS = 0 V) for 0-60 h and on-state (V_GS = 2 V and V_DS = 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.

Comparative studies of MOS-gate/oxide-passivated AlGaAs/InGaAs pHEMTs by using ozone water oxidation technique

Al0.22Ga0.78As/In0.24Ga0.76As pseudomorphic high-electron-mobility transistors (pHEMTs) with metal-oxide-semiconductor (MOS)-gate structure or oxide passivation by using ozone water oxidation treatment have been comprehensively investigated. Annihilated surface states, enhanced gate insulating property and improved device gain have been achieved by the devised MOS-gate structure and oxide passivation. The present MOS-gated or oxide-passivated pHEMTs have demonstrated superior device performances, including superior breakdown, device gain, noise figure, high-frequency characteristics and power performance. Temperature-dependent device characteristics of the present designs at 300–450 K are also studied.

Investigations of Novel

A novel Γ-gate Al0.24Ga0.76As/In0.15Ga0.85As metal-oxide-semiconductor (MOS) high-electron-mobility transistor (MOS-HEMT) by using methods of ozone water oxidation and shifted exposure has been comprehensively investigated. Effective gate-length reduction, improved gate insulation, and formations of a field plate and a full surface passivation within the drain-source region are simultaneously achieved. The present Γ-gate MOS-HEMT has demonstrated superior device performances, including improvements of 523% (12.8%) in two-terminal gate-drain breakdown, 137% (36.1%) in on-state drain-source breakdown, 16.1% (11.8%) in maximum extrinsic transconductance (gm, max), 34.5% (9.7%) in intrinsic voltage gain (AV), 27.8% (16.2%) in power-added efficiency, 34.5% (19.8%) in minimum noise figure (NFmin) , and 28%/39.3% (11.4%/21.6%) in unity-gain cutoff frequency/maximum oscillation frequency (fT/fmax), as compared to a conventional Schottky-gate (MOS-gate) device fabricated upon the same epitaxial structure by using an identical optical mask set. Investigations of optimum extracted parasitics, small-signal device parameters, and high-temperature device characteristics at 300 K-450 K are also made in this work.

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This article reports an InAlAs/InGaAs metal oxide semiconductor metamorphic high electron mobility transistor (MOS-MHEMT) by using ozone water oxidation treatment to form an 8.5 nm thick gate oxide with a superior surface flatness. The proposed MHEMT with (without) ozone treatment has demonstrated a lower gate leakage density of 2 μA/mm (0.48 mA/mm) at V gd = -5 V, improved output conductance (g d ) of 8.5 (33.1) mS/mm, gate-voltage swing of 0.9 (0.45) V, enhanced output power of 18.34 (13.43) dBm, and power-added efficiency of 46.8 (26.3)% at 300 K, with gate dimensions of 1 × 200 μm 2 .

-Gate MOS-HEMTs by Ozone Water Oxidation and Shifted Exposure Techniques

This paper reports an AlGaN/GaN metal-oxidesemiconductor high electron mobility transistor (MOS-HEMT) with stacked Al2O3/HfO2 gate dielectrics by using hydrogen peroxide (H2O2) oxidation/sputtering techniques. The present Al2O3/HfO2 bi-layer MOS-HEMTs can combine the advantages of both gate dielectrics and have demonstrated enhanced drive current, breakdown, and power characteristics.

InAlAs/InGaAs MOS-MHEMTs by Using Ozone Water Oxidation Treatment

A three-terminal optical sensor by using an aluminum-doped zinc oxide (AZO)-gated Al0.2Ga0.8As /In0.2Ga0.8As high electron mobility transistor (AZO-HEMT) on a GaAs substrate is demonstrated in this report. Optical responses under illumination of different wavelengths are investigated, as compared to a conventional Au-gated HEMT device. Experimental results demonstrate that the present design is promising for tunable optical sensing applications.

A Device Performance Study of Stacked Gate Dielectrics AlGaN/GaN MOS-HEMTs by Mixed Oxide Thin Film Growth Techniques

This work investigates device performances of an AlGaAs/InGaAs metal-oxide-semiconductor pseudomorphic high electron mobility transistor (MOS-pHEMT) by using ozone water oxidation treatment. Experiment results indicate that the studied MOS-pHEMT has demonstrated superior device characteristics as compared to a conventional pHEMT without oxidation treatment on the same epitaxial structure. The studied MOS (conventional)-pHEMT exhibits improved power-added-efficiency (P.A.E.) of 39.6 (36) %, unity-gain cut-off frequency (fT) of 19.3 (16.8) GHz, maximum oscillation frequency (fmax) of 30.6 (26.7) GHz, minimum noise figure (NFmin) of 1.21 (1.48) dB, and excellent two-terminal gate-drain breakdown voltage (BVGD) of − 43.1 (−7.9) V, respectively