This work reports the use of undoped porous amorphous/nanocrystalline hydrogenated silicon (a/nc-Si:H) thin films produced by hot wire chemical vapour deposition (HW-CVD) as ethanol detector above 50ppm and as a primary fuel cell where a power of 4μW/cm2 was obtained in structures of the type glass/ITO/i-a-nc-Si:H/Al. The porous silicon looks like a sponge constituted by grains and cluster of grains that determines the type of surface morphology and the behaviour of the structure under the presence of vapour moisture. Apart from that, the detector/device performances will also depend on the type of interlayer and interfaces with the metal contacts. The sponge like structure adsorbs the OH groups in uncompensated bonds, which behave as donor-like carriers, leading to an increase in the current flowing through the material, directly dependent on the ethanol vapour pressure. The corresponding role of the components of the microstructure on this detector was investigated by spectroscopic impedance. The response time of the current of the sensor and its recovery time are in the range of 10-50s at room temperature. © 2004 Elsevier B.V. All rights reserved.

In this paper, we investigate the optoelectronic properties and the photodegradation of amorphous silicon films produced by the hot wire plasma assisted technique (HWPA-CVD). We observed that hydrogen dilution in the gas phase plays an important role in the time dependence of the photoconductivity, which is correlated with an enhancement of defect density. We also compare the degradation of these films with those produced by plasma enhanced and by hot wire chemical vapour deposition techniques (PECVD and HW-CVD) and we found lower time dependence for the photodegradation of the films produced by HWPA-CVD technique © 2003 Elsevier B.V. All rights reserved.

The fabrication of high field-effect mobility ZnO thin film transistor (ZnO-TFT) at room temperature by rf magnetron sputtering was discussed. The ZnO used was deposited onto borosilicate glass substrate with a thickness of 1 mm with 100 x 100 mm surface area, coated with a 200 nm sputtered ITO film. The hall mobilities of about 2 cm2 / V s and a carrier concentration of 3 x 1016cm-3 were measured for the films with lower resistivity. It was observed that the ZnO-TFT presented an average optical transmission of 80% in the visibility part of the spectrum.