Transistor gate electrode

Figure 12.5. Photograph of microdispensing system depositing an inorganic dielectric dispersion onto a patterned, metallized polyester film. The pattern is of a transistor gate electrode array. The microdispensing head atomizes the dispersion, generating a liquid spray much like a dual orifice atomizer found on an airbrush.

Electron tunnelling tlirough monolayers of long-chain carboxylic acids is one aspect of interest since it was assumed tliat such films could be used as gate electrodes in field-effect transistors or even in devices depending on electron tunnelling [24, 26, 35, 36, 37 and 38]- It was found, however, tliat tlie whole subject depends critically on... 

Fig. 6. Molecular transistor based on a microelectrode array. P is a polymer layer that can be switched conductive or nonconductive by the potential of the gate electrode (from ref.

As a switching device capable for ultra-large-scale integrated circuits (ULSIs) comprises only one Coulomb island with two leads (electrodes) and a capacitively coupled gate electrode attached to it. This system works as a simple on/off switch and it is often called the SE transistor. Applying a voltage to the outer electrodes of this circuit may either cause sequential transfer of electrons onto and out of the central island or to have no charge transport, i.e. the transistor remains in non-conductive state. The result... 

Figure 2. Scanning electron micrograph of a SE transistor with source and drain ( + U/2 and —U/2, respectively) feeding the central island (Insel), which is capacitively coupled to a gate electrode. The size of the central island is about 60 nm x 60 nm.

The TFTs are made on transparent glass substrates, onto which gate electrodes are patterned. Typically, the gate electrode is made of chromium. This substrate is introduced in a PECVD reactor, in which silane and ammonia are used for plasma deposition of SiN as the gate material. After subsequent deposition of the a-Si H active layer and the heavily doped n-type a-Si H for the contacts, the devices are taken out of the reactor. Cr contacts are evaporated on top of the structure. The transistor channel is then defined by etching away the top metal and n-type a-Si H. Special care must be taken in that the etchant used for the n-type a-Si H also etches the intrinsic a-Si H. Finally the top passivation SiN, is deposited in a separate run. This passivation layer is needed to protect the TFT during additional processing steps. 

AFID = alkali-flame ionization detection FID = flame ionization detection FPD = flame photometric detection GC = gas chromatography IGEFET = interdigitated gate electrode field-effect transistor ITMS = ion trap mass spectrometry MIMS = multiphoton ionization mass spectrometry MS = mass spectrometry... 

Brothers CP. 1990. Evaluation of an interdigitated gate electrode field-effect transistor for detecting organophosphorus compounds. Wright-Patterson AFB, OH Air Force Institute of Technology. NTISNo. AD-A23 0-161. 

Kolesar ES, Wiseman JM. 1989. Interdigitated gate electrode field effect transistor for the selective detection of nitrogen dioxide and diisopropyl methylphosphonate. Anal Chem 61(21) 2355. 

Single molecule Cgo based transistors were also fabricated by depositing a diluted Cgo toluene solution onto a pair of gold electrodes. The whole structure was built on an insulating Si02 layer on top of a doped Si wafer that was used as the gate electrode to modulate the electrostatic potential of the Cgo molecule trapped in the middle of the junction (see Fig. 14). The observed 1-V characteristics were... 

The conductance of MWCNTs is quantized. The experimental setup to measure the conducting properties involved the replacement of an STM tip with a nanotube fiber that was lowered into a liquid metal to establish the electrical contact. The conductance value observed corresponded to one unit of quantum conductance (Go = 2e /h = 12.9 kQ ). This value may reflect the conductance of the external tube because, for energetic reasons, the different layers are electrically insulated [150]. Finally, the conductance of semiconductor nanotubes depends on the voltage applied to the gate electrode their band gap is a function of their diameter and helicity [145] and the ON/OFF ratio of the transistors fabricated with semiconductor nanotubes is typically 10 at room temperature and can be as high as 10 at... 

Electrodes are attached to the p-type block and to the n-type channel. The electrodes attached to the /3-type channel are known as the source (negative electrode which provides electrons) and the drain (positive electrode). The electrode attached to the //-type block is known as the gate electrode. A low voltage (typically 6 V) is applied across the source and drain electrodes. To fulfill the transistor s role, as amplifier or switch, a voltage is applied to the gate electrode. Electrons flow into the //-type semiconductor but... 

Metal oxide semiconductor field-effect transistors (MOSFETs) are field effect transistors with a thin film of silicon dioxide between the gate electrode and the semiconductor. The charge on the silicon dioxide controls the size of the depletion zone in the polype semiconductor. MOSFETs are easier to mass produce and are used in integrated circuits and microprocessors for computers and in amplifiers for cassette players. Traditionally, transistors have been silicon based but a recent development is field-effect transistors based on organic materials. 

Thin-fihn transistors have been fabricated by depositing 50 nm of CdS onto SiOz-covered n Si and evaporating two A1 elechodes (source and drain) onto the CdS [45]. Similar devices were also made using CdS deposited on polyimide substrates with three (source, drain, and gate) evaporated metal electrodes and various sputtered insulator layers for the gate electrode. 

Fig. 9. A Schottky barrier gate used in the metal-semiconductor field-effect transistor (MESFET) in AT T gallium arsenide microchips. The tiny gate is only one micrometer wide (1/25,400 inch). The gate electrode is deposited before the ion-implantation process so that the gate material will shade the channel under it from the ion rain that doses the exposed material. (AT T Technology)...

FET type humidity sensor. Although sensors based on a field-effect transistor (FET) appear to hold promise as a small and low-cost intelligent sensor, relatively few people have been engaged in the research on FET type sensors in Japan. In this respect, it is remarkable that a FET type humidity sensor was developed recently by Hijikigawa of Sharp Corp (9). The sensor is also worth notice as a new type of humidity sensor, which utilizes changes in electric capacitance of humidity sensitive membrane interposed between double gate electrodes. 

An OTFT comprises three electrodes (source, drain, and gate), a gate dielectric layer, and an organic or polymer semiconductor layer. In operation, an electric field is applied across the source-drain electrodes, and the transistor is turned on when a voltage (VG) is applied to the gate electrode, which induces a current flow (fD) from the source electrode to drain electrode. When VG = 0, the transistor is turned off, fD should in theory be 0, that is, no current is flowing. 

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