This paper discusses the influence of deposition conditions on in-situ As doped amorphous silicon emitter films used in NPN RF bipolar transistors. In-situ As doped amorphous and/or polysilicon layers improve electrical performance in BiCMOS devices by reducing the number of process steps and eliminating issues associated with implanted polysilicon on high aspect ratio topographies (plug effect). This study was made using a vertical furnace configuration capable of 150 wafer loads. Because adsorbed AsH3 decomposition species tightly bind to the active surface sites and inhibit the deposition rate, the process recipe is complex. Predictable bipolar parametrics require control of the As diffusion profile within the base region after activation, so a thorough understanding of emitter film growth and dopant incorporation is necessary.
Reducing specific contact resistivity of the silicide to silicon interface is advantageous to achieve high planar density and high drive current FET devices. Measuring the differential resistivities at different low voltage bias conditions of four terminal Kelvin test structures with a range of contact sizes has proven particularly effective in characterizing the linearity behavior and specific contact resistivity. This study shows that adding laser activation annealing for an n+ doped silicon contacted by a standard NiPt silicide is found to significantly improve the contact electrical properties. Initial results with only rapid thermal anneal activation show a size dependence of the contact resistivity with non-linear behavior exhibiting maximum resistance at zero bias, and contact resistivities ranging from 4×10-8 Ω-cm2 to 4×10-7 Ω-cm2. Adding laser anneal after the rapid thermal anneal gives ohmic behavior, for contact down to 50nm in size, with a specific contact resistivity of 1×10-8 Ω-cm2. The metal-to-silicide contact resistance was measured separately using a novel test structure and it was confirmed to be negligible. We describe our device structure, our experimental methodology, and the implications of our results for future devices.
InGaN/GaN MQWs are grown on c-plane sapphire substrates using a low pressure metal organic vapor phase epitaxy (MOVPE) system. Trimethylgallium (TMGa), Triethylgallium (TEGa), Trimethylindium (TMIn) and ammonia were used as precursors for Ga, In and N, respectively and the growths were carried out at low temperature. Structural properties of grown MQWs are characterized using atomic force microscopy (AFM), and scanning electron microscope (SEM) and x-ray diffraction technique (XRD) is used to calculate the Indium incorporation in these MQWs. Surface morphologies over large areas of InGaN/GaN MQWs are observed using the tapping mode AFM; results indicate the surface roughness depends on the barrier thickness. Density of V- defects, effect of barrier width on the surface morphology and also on V-defect density will be presented and discussed.
During in vivo angiogenesis, the ECs that form new blood vessels from existing vessels re-activate, migrate, proliferate and reorganise into tubes. Several biological assays have been developed to assess candidate angiogenesis therapeutics  but not all of them incorporate all of the four EC-associated activities required for forming new blood vessels. However, the rat aorta ring assay, which is widely used as a screen for anti-angiogenic activity, involves EC re-activation, migration, proliferation and reorganisation and as a result of these processes the formation of EC-derived micro-capillaries occur over a longer time course than other biological assays . Therefore, although the rat aorta ring assay is ex vivo it is considered to more closely mimic in vivo conditions and it has been used to successfully identify the anti-angiogenic therapeutic, Muparfostat (PI-88), which is already in phase III cancer trials . We show here that adjustments to the concentration of heat inactivated foetal bovine serum can be made in this widely used bioassay so that the anti- or pro-angiogenic effects of an added compound on EC cells can be monitored (measured by determining the speed and extent of angiogenesis over time). Other commonly used in vitro assays examine the individual component steps of angiogenesis and are used to define the cellular mode-of-action of a particular compound over a shorter time frame . 2b1af7f3a8