Zhang, S.a b, Liao Xu Martins Fortunato Kong X. a Y. a. "
The diphasic nc-Si/a-Si:H thin film with improved medium-range order."
Journal of Non-Crystalline Solids. 338-340 (2004): 188-191.
AbstractA series of silicon film samples were prepared by plasma enhanced chemical vapor deposition (PECVD) near the threshold from amorphous to nanocrystalline state by adjusting the plasma parameters and properly increasing the reactions between the hydrogen plasma and the growing surface. The microstucture of the films was studied by micro-Raman and Fourier transform infrared (FTIR) spectroscopy. The influences of the hydrogen dilution ratio of silane (R H = [H2]/[SiH4]) and the substrate temperature (Ts) on the microstructural and photoelectronic properties of silicon films were investigated in detail. With the increase of RH from 10 to 100, a notable improvement in the medium-range order (MRO) of the films was observed, and then the phase transition from amorphous to nanocrystalline phase occurred, which lead to the formation of diatomic hydrogen complex, H 2 * and their congeries. With the increase of T s from 150 to 275 °C, both the short-range order and the medium range order of the silicon films are obviously improved. The photoconductivity spectra and the light induced changes of the films show that the diphasic nc-Si/a-Si:H films with fine medium-range order present a broader light spectral response range in the longer wavelength and a lower degradation upon illumination than conventional a-Si:H films. © 2004 Elsevier B.V. All rights reserved.
Águas, H.a, Pereira Ferreira Ramos Viana Andreu Vilarinho Fortunato Martins L. a I. a. "
Effect of an interfacial oxide layer in the annealing behaviour of Au/a-Si:H MIS photodiodes."
Journal of Non-Crystalline Solids. 338-340 (2004): 810-813.
AbstractThis work presents a study on the effect of an interfacial silicon oxide layer placed between Au and a-Si:H MIS (metal-insulator-semiconductor) photodiodes in their performances, by stopping the Au diffusion towards the a-Si:H. The results show that the Au diffuses very easily to the oxide free a-Si:H surface, even at room temperature, degrading the photodiode performance. On the other hand, the MIS photodiodes with the interfacial oxide show an improvement of their characteristics after annealing, function of its thickness, and degree of film's compactness. This effect is associated with the presence of oxide of thicknesses ≥5 Å at the Au/a-Si:H interface that prevents the Au diffusion and improves the photodiode characteristics, which does not happen when the interfacial oxide is absent. © 2004 Elsevier B.V. All rights reserved.