ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTIon-channel sensorsMasao. Sugawara, Koichi. Kojima, Hiroyuki. Sazawa, and Yoshio. UmezawaCite this: Anal. Chem. 1987, 59, 24, 2842–2846Publication Date (Print):December 15, 1987Publication History Published online1 May 2002Published inissue 15 December 1987https://pubs.acs.org/doi/10.1021/ac00151a004https://doi.org/10.1021/ac00151a004research-articleACS PublicationsRequest reuse permissionsArticle Views649Altmetric-Citations165LEARN ABOUT THESE...

This paper describes the fabrication of a SiC-based high electron mobility transistor (HEMT). A single-crystal 3C–SiC layer was grown on C-face 4H–SiC substrate, and 2D gas induced at 3C–SiC/4H–SiC heterointerface due to unique polarization physics. The measured Hall 2DEG 586 cm2/V s room temperature. Source, gate, drain electrodes were fabricated surface. current for SiC-HEMT be 47.5 mA/mm, transconductance estimated 13.5 mS/mm.

Using an atmospheric metal-organic chemical vapor deposition system, we passivated GaAs with AlN prior to atomic layer of Al2O3. This passivation incorporated nitrogen at the Al2O3/GaAs interface, improving capacitance-voltage (C–V) characteristics resultant metal-oxide-semiconductor capacitors (MOSCAPs). The C–V curves these devices showed a remarkable reduction in frequency dispersion accumulation capacitance. conductance method various temperatures, extracted interfacial density states...

We epitaxially grew a single-domain 3C layer on step-controlled C-face 4H-SiC substrate to create 3C/4H-SiC heterostructure. The effectiveness of using such grow thin highly crystalline was demonstrated. heterostructure exhibited an electron Hall mobility 7224 cm2/V s at 32 K, which is more than one order magnitude higher the best value reported for this structure. From comparison with 134 m2/V structure multi-domain layer, we attribute high formation. nearly constant sheet carrier density...

The effect of Mn-doping into a GaN buffer layer grown by metal organic chemical vapor deposition (MOCVD) on the reduction in leakage current high-electron-mobility transistors (HEMTs) was investigated. Both surface morphology and crystallinity maintained their quality even after heavy Mn-doping. sheet resistance films increased with increasing amount origin semi-insulating is considered to be electron scattering carrier compensation mechanism involving deep levels generated Mn impurity. When...

This paper presents a compressive study on the fabrication and optimization of GaAs metal–oxide–semiconductor (MOS) structures comprising Al2O3 gate oxide, deposited via atomic layer deposition (ALD), with an AlN interfacial passivation prepared in situ metal–organic chemical vapor (MOCVD). The established protocol afforded self-limiting growth atmospheric MOCVD reactor. Consequently, this enabled successive MOCVD-formed ALD-formed layers substrate. effects thickness, post-deposition anneal...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of the membrane surface charge on host-guest complex valinomycin in a synthetic lipid monolayer at air-water interfaceMasao Sugawara, Hiroyuki Sazawa, and Yoshio UmezawaCite this: Langmuir 1992, 8, 2, 609–612Publication Date (Print):February 1, 1992Publication History Published online1 May 2002Published inissue 1 February 1992https://pubs.acs.org/doi/10.1021/la00038a051https://doi.org/10.1021/la00038a051research-articleACS...

First-principles calculations are carried out to estimate the spontaneous polarization and energy band gap bowing in YxAlyGa1-x-yN alloys lattice-matched GaN. The ground state properties of computed by using pseudopotential-planewave method conjunction with generalized gradient approximation density functional theory. We find nonlinear behavior energies values depend on atomic geometry unit cell, especially that yttrium.

GaAs-based metal–oxide–semiconductor heterostructure field-effect transistors (MOSHFETs) with Al2O3 gate oxide and in situ AlN passivation were investigated. Passivation improved the quality of MOS interfaces, leading to good control gate. The devices had a sufficiently small subthreshold swing 84 mV decade−1 drain current vs voltage curves, as well negligible frequency dispersions nearly zero hysteresis capacitance curves. A maximum 630 mA/mm peak effective mobility 6720 cm2 V−1 s−1 at...

First-principles calculations are carried out to estimate the spontaneous polarization and band gap bowing in ScxAlyGa1 − x yN alloys lattice-matched GaN based on density functional theory together with a pseudopotential plane-wave method. The results indicate nonlinear behavior of energies similar that YxAlyGa1 (Shimada et al 2011 J. Appl. Phys. 110 074114). magnitude is larger than wide range mole fraction Ga. We find atomic configuration Sc affects yN. Another finding apparent deviation...

Abstract Metal‐insulator‐semiconductor (MIS) heterostructure field‐effect transistors (HFETs) fabricated with HfAlO as a gate insulator high dielectric permittivity are demonstrated to achieve true enhancement‐mode operation no leakage and drain current density. Insertion of the layer allows for forward bias voltages up +8 V without (maximum density 1.2×10 –5 mA/mm at bias) under direct operation. Utilizing extended swing, maximum 767 is achieved, substantially higher than that non‐insulated...

Abstract We report on metal‐insulator‐semiconductor (MIS) heterostructure field‐effect transistor (HFET) with AlO x gate insulator formed by metal‐organic chemical vapor deposition (MOCVD) method designed for achieving low leak and less current collapse. The was successively onto the MOCVD‐grown AlGaN/GaN using trimethylaluminum (TMA) n‐butyl ether as precursors. Flowing gas during /AlGaN interface formation mainly consisted of ammonia nitrogen aim preventing N vacancy creation oxide AlGaN...

We report the influence of size hollow cores that extend from micropipes in SiC substrates on dc characteristics AlGaN∕GaN high-electron mobility transistors (HEMTs) fabricated substrates. Significant deterioration HEMTs vicinity with a diameter 5μm was observed, while no major observed for around whose diameters were 1.5 and 3μm. A clear correlation between free carrier densities at peripheries using micro-Raman imaging. The high carriers relatively large suggested to be cause cores. device...

Abstract We report the rf‐MBE growth and characterizations of AlGaN/GaN heterostructures their HEMTs on vicinal sapphire (0001) substrates. Vicinal angle dependences property (surface morphologies 2DEG mobility) in are investigated. It is found that surface morphology mobility greatly improved by using Furthermore, gate‐leakage current AlGaN/GaN‐based HEMTs, which important for device operation, suppressed due to improvement reduction dislocation density heterostrucutes. (© 2008 WILEY‐VCH...

Abstract To clarify the effect of micropipes in SiC substrates on AlGaN/GaN HEMT performance, we fabricated HEMTs, with precise positioning, and around hollow core at end substrate an overgrown epitaxial layer evaluated DC characteristics devices. The devices showed poor pinch‐off characteristic a large gate leakage current. This deterioration device performance became insignificant longer distances from core, there were no observed differences distance 40 μm. Raman investigation revealed...

We performed first-principles calculations of the spontaneous polarization and electronic band structures in Sc x Al y Ga 1- - N alloys assuming their growth on freestanding GaN. found an apparent deviation from Vegard's law lattice constants lattice-matched to It was supposed that this comes different bonding properties IIIB IIIA nitrides, resulting crystal structures, such as hexagonal wurtzite structures. As reported our previous report Y [K. Shimada et al.: J. Appl. Phys. 110 (2011)...

AlGaN/GaN HFETs were fabricated around micropipes and on a domain boundary in semi-insulating silicon carbide (SI-SiC) substrate the DC characteristics of devices measured. Devices micropipe showed no pinch-off or large gate leakage. The boundaries degradation performances, even though an X-ray topographic analysis indicated that crystal imperfections, due to defects, propagated GaN layer across hetero interface. Based these results, we concluded degrades does not affect characteristics....

A Ti/Au/Al/Ni/Au metallization scheme is demonstrated to achieve a more than tenfold reduction in contact resistance AlGaN/GaN heterostructure devices. The specific resistivity of the 9.1×10-7 Ω cm2. insertion gold layer between titanium and aluminum proposed structure prevents from diffusing into during annealing, allowing concentrate at AlGaN interface thus promoting reaction AlGaN/GaN. new characterized by penetration nitride layer, providing direct with two-dimensional electron gas.

Abstract A deterioration mechanism of DC characteristics AlGaN/GaN high‐electron mobility transistors (HEMTs) fabricated around hollow cores that extend from micropipes in SiC substrates was studied. Various sizes were investigated to study the influence size dependence. Prominent HEMTs vicinity with a diameter 5 μm observed, while no major observed for whose diameters 1.5 and 3 μm. Clear correlation between free carrier densities at peripheries using micro‐Raman imaging. The high density...