Miniaturized planar back-side contact transducers (BSC) with chemically modified gold surface have been utilized as electrochemical sensors. The electrodes have been functionalized by sequential immobilization of aryl diazonium salts or alkanethiols and short peptide Gly-Gly-His. The applicability of gold substrates modified with aryl diazonium salts in voltammetric detection of copper(II) ions in aqueous solutions has been studied. The combination of two fundamental elements of the solid-state electrode, i.e. back-side contact (BSC) gold sensor and self-assembled monolayers, allowed one to obtain reliable miniaturized copper(II) ion sensors. It can have important future applications in environmental sensing or in implantable biodevices.
Terahertz (THz) radiation detection by junctionless metal-oxide-semiconductor field-effect transistors (JL MOSFETs) was studied and compared with THz detection using conventional MOSFETs. It has been shown that in contrast to the behavior of standard transistors, the junctionless devices have a significant responsivity also in the open channel (low resistance) state. The responsivity for a photolithographically defined JL FET was 70 V/W and the noise equivalent power 460 pW/√Hz. Working in the open channel state may be advantageous for THz wireless and imaging applications because of its low thermal noise and possible high operating speed or large bandwidth. It has been proven that the junctionless MOSFETs can also operate in a zero gate bias mode, which enables simplification of the THz array circuitry. Existing models of THz detection by MOSFETs were considered and it has been demonstrated that the process of detection by these junctionless devices cannot be explained within the framework of the commonly accepted models and therefore requires a new theoretical approach.
Articles you may be interested inFocused ion beam modification of atomic force microscopy tips for near-field scanning optical microscopy Fabrication of a nanosize metal aperture for a near field scanning optical microscopy sensor using photoresist removal and sputtering techniques Novel scanning near-field optical microscopy/atomic force microscope probes by combined micromachining and electron-beam nanolithographyIn scanning near field optical microscope ͑SNOM͒, an optical probe with aperture diameter well below the optical wavelength is moved over the sample. The sample-probe distance control is one of the key problems in SNOM. Our earlier approach allowed for fabrication of the piezo-SNOM/ atomic force microscopy ͑AFM͒ probe, however, reproductivity of the process and optical quality of the device were not satisfactory. Now we report an innovative processing sequence, which offers highly reproductive batch processing, typical for semiconductor technology and renders it possible to produce cantilevers playing role of an AFM detector as well as a nanoaperture detector. Moreover, illumination of the aperture is easier because of a wide input opening and its big cone angle. The throughput is in the range of 10 Ϫ5 and higher. Apertures in hollow pyramids have been formed by direct ion beam drilling with a focused beam of 30 keV Ga ϩ ions. Direct focused ion beam ͑FIB͒ drilling is a reproducible process for hole formation at the 30-100 nm diameter range. Formation of smaller apertures is possible if a special FIB drilling/deposition procedure is applied.
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