In this work optical and semiconductor characteristics of gallium oxide based thin films are studied. This material has important electro-optic applications and offers possibilities for semiconductor applications in heavy metal oxide semiconductor technology. In this study thin films of PbO-Bi2O3-Ga2O3 were deposited by reactive sputtering. Two targets with different concentrations of Nd2O3 (0.2 and 1.0 wt%) were prepared. Thin films were deposited by pure Ar plasma, at 5 mTorr pressure and RF power of only 20 W. Films were deposited on three inch diameter substrates of (100) silicon wafers. Optical UV-Vis-Nir transmittance and FTIR analyses showed that the films are transparent in the visible and middle infrared region of the electromagnetic spectrum. The refractive index of the films was of about 2.3, as measured by ellipsometry; Rutherford Backscattering Spectroscopy (RBS) analyses were employed for the compositional analysis of the films. For the electrical characterization it was used metallic electrodes, and the final structure obtained is a capacitor structure where the gallium oxide film plays the role of a dielectric. In the current versus voltage (IxV) analyses, the samples with 1.0 wt% of Nd2O3 show semiconductor characteristics similar to the ones obtained for the degenerated transistors. The electric characteristics of these films allow applications with electro-optic devices (phototransistors and photo detectors).

Filmes finos de PMMA foram preparados a partir de solução e expostos ao plasma de CF4+H2, visando mudar o Índice de Refração (I.R.) da superficie do PMMA através da fluoração. Os filmes de PMMA expostos ao plasma, denominados de filmes ópticos, foram caracterizados usando as técnicas: ESCA, RBS, FTIR, gravimetria, ângulo de contato, refratometria e elipsometria. Os resultados revelaram que as superfícies de PMMA foram revestidas com uma fina camada de hidrofluorcarbono polimérico, com espessuras variando entre 0,43 e 0,49mim. A camada de hidrofluorcarbono polimérico na superfície do PMMA foi responsável pela significante redução do seu I.R. de 1,49 para 1,43. A concentração de flúor nessa camada aumentou gradualmente em função da profundidade, sendo menor na sua superficie. Como o átomo de flúor é responsável pela redução do I.R., concluiu-se que o I.R. no revestimento fluorado do filme óptico variou também de forma gradual. A técnica de polimerização por plasma de CF4+H2 mostrou-se útil para modificar in situ os I.R. da superfíces de guias de ondas e fibras ópticas poliméricas, visando reduzir as perdas e aumentar a velocidade de transmissão de dados.

Fluorinated PMMA optical films were obtained using the CF4+H2 plasma polymerisation technique. The characterisation analysis: ESCA, RBS, FTIR, gravimetry, contact angle, refractometry and ellipsometry, revealed that a hydrofluorcarbon polymer was deposited on the optical films exposed to the plasma. Fluorine concentration increased gradually with the fluorinated film depth (0.43-0.49mum). A refractive index 1.42-1.43 was found on the surface of the fluorinated films, lower than the PMMA (1.49). This fluorinated layer could present a gradient refractive index, being reciprocal of the Fluorine concentration. The potential advantages to obtain graded-index polymer waveguides and optical fibres are loss reductions and higher transmission rates.