We investigated emulsions stabilized with particles of layered hexaniobate, known as a semiconductor photocatalyst, and photocatalytic degradation of dyes in the emulsions. Hydrophobicity of the niobate particles was adjusted with the intercalation of alkylammonium ions into the interlayer spaces to enable emulsification in a toluene-water system. After the modification of interlayer space with hexylammonium ions, the niobate stabilized water-in-oil (w/o) emulsions in a broad composition range. Optical microscopy showed that the niobate particles covered the surfaces of emulsion droplets and played a role of emulsifying agents. The niobate particles also enabled the generation of oil-in-water (o/w) emulsions in a limited composition range. Modification with dodecylammonium ions, which turned the niobate particles more hydrophobic, only gave w/o emulsions, and the particles were located not only at the toluene-water interface but also inside the toluene continuous phase. On the other hand, interlayer modification with butylammonium ions led to the formation of o/w emulsions. When porphyrin dyes were added to the system, the cationic dye was adsorbed on niobate particles at the emulsion droplets whereas the lipophilic dye was dissolved in toluene. Upon UV irradiation, both of the dyes were degraded photocatalytically. When the cationic and lipophilic porphyrin molecules were simultaneously added to the emulsions, both of the dyes were photodecomposed nonselectively.

We have realized InP/InGaAs composite-channel metal–oxide–semiconductor field-effect transistors with both selectively regrown n+-InGaAs source/drain regions and Al2O3 as a gate dielectric. A 100-nm-long channel was fabricated by laterally buried regrowth in a channel undercut by metalorganic vapor phase epitaxy. The carrier density of the regrown layer was 2.9×1019 cm-3. A drain current Id of 1.34 mA/µm was achieved at a drain voltage Vd of 1 V and a gate voltage Vg of 3 V. A transconductance gm of 817 µS/µm at Vd = 0.65 V was also observed at the same time. The improvement in the subthreshold slope can be explained by the decrease in dielectric/semiconductor interface trap density.

We have demonstrated an InP/InGaAs composite-channel metal–oxide–semiconductor field-effect transistor with a selectively regrown n+-InGaAs source/drain formed by metal organic vapor-phase epitaxy. A 150-nm-long channel was fabricated using a dummy gate and by laterally buried regrowth in the channel undercut. The gate stack was formed after regrowth by replacing the dummy gate. The carrier density of the regrown layer was 4.9×1019 cm-3. The maximum drain current at a drain voltage Vd = 1 V and a gate voltage Vg = 3 V was 0.93 mA/µm and the maximum transconductance was 0.53 mS/µm at Vd = 0.65 V.

We demonstrated a high-mobility InP 5 nm/InGaAs 12 nm composite channel MOSFET with MOVPE regrown n + -source/drain region for low series resistance and high source injection current. A gate dielectric was SiO 2 and thickness was 20 nm. A carrier density of regrown InGaAs source/drain layer was over 4 × 10 19 cm í3 . In the measurement of submicron (= 150 nm) device, the drain current was 0.93 mA/μm at V g = 3 V, V d = 1 V and the peak transconductance was 0.53 mS/ȝm at V d = 0.65 V, respectively. The channel length dependence of transconductance indicated the good relativity.

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