The crystallization of amorphous Si induced by Al during heat treatment has been investigated by cross section and plan view transmission electron microscopy. The lowest temperature of Al induced crystallization of amorphous Si was found to be 440 K. The crystallization temperature, however, depends on the thickness of Al layers in layered structures and on the concentration of Al in co-deposited layers below 1-nm-layer thickness and 15 at.% of Al concentration, respectively. Al-induced crystallization in layered structures starts at the Al/amorphous Si interfaces and is located close to them. The amount of crystallized Si depends on the quantity of Al and on the temperature and increases with them. The mechanism of crystallization involves intermixing of Al with Si and the formation of an alloy of high metal concentration in the amorphous/crystalline interface. When the formation of this alloy is not assured due to low Al concentration, then crystallization does not start or the process of crystallization stops. In Al induced crystallization the nucleation of polycrystalline Si grains rather than their crystal growth is affected.
Abstract-A fully integrated triplexer for multi-band ultrawideband radio is presented. The triplexer utilizes a microstrip network and three combined broadside-and edge-coupled filters. It is fully integrated in a printed circuit board with low requirements on the printed circuit board process tolerance. Three flat sub-bands in the frequency band 3.1-4.8 GHz have been achieved. The group delay variation within each 500 MHz sub-band was measured to be around 1 ns. A good agreement between simulation and measurement was obtained.
Abstract-A fully integrated dipole antenna with balun for ultra-wideband (UWB) radio utilizing a flexible and rigid printed circuit board is presented in this paper. The concept in this paper is to take advantage of the respective possibilities of the rigid and the flexible part. The balun utilizes broadside-coupled microstrips and is integrated in the rigid part of the printed circuit board, whereas the radiator is placed in the flexible part. The antenna with the balun covers the Mode 1 UWB frequencyband 3.1-4.8 GHz (with margin) at VSWR<2. Furthermore, good radiation characteristics and a linear phase response are observed with measurements.
Thin-film multilayer structures of a-Si/Al/a-Si and a-Si/Sb/a-Si were deposited by electron-beam evaporation. The microstructure and the electrical properties of as-deposited and annealed (T<1370 K) thin films were determined. A p-n junction was formed between polycrystalline silicon (poly-Si) doped with Sb and a p-type Si substrate. Al and Sb were found to induce crystallization of a-Si at 600 and 700 K, respectively. After annealing to 1370 K for 60 min, the resistivities 7.0×10−3 Ω cm for the Al-Si sample and 1.4×10−2 Ω cm for the Sb-Si sample were obtained. Passivation of poly-Si grain boundaries by Sb is proposed.
Abstract-A study of the component tolerances on an ultra-wideband (UWB) low-noise amplifier designed on a conventional printed circuit board is presented in this paper. The low-noise amplifier design employs dual-section input and output microstrip matching networks for wideband operation with a low noise figure and a flat power gain. First, the effect of passive component and manufacturing process tolerances on the low-noise amplifier performance is theoretically studied by means of sensitivity analyses. Second, simulation and measurement results are presented for verification of the analytical results. It is shown that, compared with a lumped matching network design, a microstrip matching network design significantly reduces the UWB low-noise amplifier sensitivity to component tolerances.Index Terms-Low-noise amplifier (LNA), matching networks, sensitivity analysis, ultra-wideband (UWB).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.