Layer Deposition Of Thin Films Research Articles

A new thin-film Pb microsensor based on chalcogenide glasses

A new all solid-state potentiometric Pb sensor has been developed on the basis of chalcogenide glass-sensitive material by means of the pulsed laser deposition technique (PLD). The composition, structure and thickness of the deposited sensitive layer has been investigated by means of Rutherford backscattering spectrometry (RBS) and transmission electron microscopy (TEM). The sensor exhibits a high sensitivity (27–29 V/pPb) over six orders of magnitudes with short response time and low detection limit of 1×10 −7 mol/l. The selectivity, the pH interval and the long-term stability of the sensor is discussed. The combination of chalcogenide glass-sensitive materials with the method of thin-film layer deposition (PLD technique) allows to develop sensing materials with a wide spectrum of predefined properties in the thin film state, giving opportunity for the development of miniaturised thin film sensors. Such sensors can be utilised in multisensor systems for the multicomponent analysis of complex media.

Atomic Layer Deposition of thin Films Using Sequential Surface Reactions

AbstractThin films can be deposited with atomic layer control using sequential surface reactions. The atomic layer deposition (ALD) of compound and single-element films can be accomplished using the appropriate surface chemistry. This paper reviews the ALD of dielectric alumina (Al2O3) films and conducting tungsten (W) films. The Al2O3 films are deposited on submicron BN particles and the surface chemistry is monitored using Fourier transform infrared (FTIR) spectroscopy. Additional transmission electron microscopy (TEM) studies investigated the conformality of the Al2O3 growth on the BN particles. FTIR investigations of the surface chemistry during W ALD are performed on nanometer-sized Si02 particles. Additional in situ spectroscopy ellipsometry studies of W ALD on Si(100) established the W ALD growth rates. Al2O3 and W ALD both illustrate the potential of ALD to obtain conformal and atomic layer controlled thin film growth using sequential surface reactions.

Fabrication of a-Si:H Tfts at 120°C on Flexible Polyimide Substrates

ABSTRACTThe fabrication of large-area thin-film transistor (TFT) arrays on thin flexible plastic substrates requires deposition of thin film layers at relatively low temperatures since the upper working temperature of low-cost plastic films should not exceed ∼200°C. In this paper, we report a fabrication process of a-Si:H TFTs at 120°C on flexible polyimide substrates for large-area imaging applications.Kapton HN (DuPont) films 50 and 125 μm thick and 3 inches in diameter, were used as substrates. Both sides of the polyimide substrate were first covered with 0.5 μm thick a-SiNx. The TFT structure includes: 120 nm thick room-temperature sputtered Al gate, 250 nm thick PECVD deposited a-SiNx for the gate dielectric, 50 nm thick a-Si:H deposited by PECVD from silane-hydrogen gas mixture, 50 nm thick n+ a-Si:H source- and drain contacts, and roomtemperature sputtered Al top contact metallization. We used dry etching for all layers except for the gate and top metal, which were patterned using wet etchants. For purpose of TFT performance comparison, Coming 7059 glass substrates were used.The performance of the fabricated TFT and its improvement with use of optimized a-Si:H and a-SiNx quality will be presented along with a discussion of the intrinsic mechanical stress in the thin film layers will also be discussed.