Nano-Crystalline &Amorphous Silicon PhotoTransistor Performance Analysis

In this thesis, we compared electrical performance and stability of a novel nanocrystalline Si (nc-Si) thin film phototransistor (TFT) phototransistor and a regular amorphous silicon (a-Si:H) TFT phototransistor for large area imaging applications. The electrical performance parameters of nc-Si TFT phototransistor were extracted from the electrical (current-voltage) testing in dark and under illumination. The field-effect mobility is found to be around 1.2 cm2V-1s-1, the threshold voltage around 3.9V and the sub-threshold voltage slope around 0.47V/Dec. Optical properties of nc-Si TFT phototransistor have been evaluated under the green light illumination in the range of 1014 – 1017 lum, and the photocurrent gain and the external quantum efficiency were extracted from the experimental results. By comparing the results with those for a-Si:H TFTs measured under the same conditions, we found that nc-Si TFT has higher photo current gain under low illumination intensity, 5 ×1014 to 7 ×1015 lum. This thesis shows the relations bewteen the photo current gain, the external quantum efficiency, TFT drain and TFT gate bias; the photo current gain and the external quantum efficiency can be controlled by the Vds and the Vgs

Spatial separation of state- and size-selected neutral clusters

We demonstrate the spatial separation of the prototypical indole(H2O) clusters from the various species present in the supersonic expansion of mixtures of indole and water. The major molecular constituents of the resulting molecular beam are H2O, indole, indole(H2O), and indole(H2O)2. It is a priori not clear whether such floppy systems are amenable to strong manipulation using electric fields. Here, we have exploited the cold supersonic molecular beam and the electrostatic deflector to separate indole(H2O) from the other molecular species as well as the helium seed gas. The experimental results are quantitatively explained by trajectory simulations, which also demonstrate that the quantum-state selectivity of the process leads to samples of indole(H2O) in low-lying rotational states. The prepared clean samples of indole(H2O) are ideally suited for investigations of the stereodynamics of this complex system, including time-resolved half-collision and diffraction experiments of fixed-in-space clusters. Our findings clearly demonstrate that the hydrogen bonded indole(H2O) complex behaves as a rigid molecule under our experimental conditions and that it can be strongly deflected.Comment: 7 pages, 5 figure