New York City in the world at 103, including former Mayor Michael Bloomberg. New York also had the highest density of millionaires per capita among major U.S. cities in 2014, at 4.6% of residents. New York City is one of the relatively few American cities levying an income tax (currently about 3%) on its residents. New York is a global hub of business and commerce. The city is a major center for banking and finance, retailing, world trade, transportation, tourism, real estate, new media, traditional media, advertising, legal services, accountancy, insurance, theater, fashion, and the arts in the United States; while Silicon Alley,
Polycrystalline silicon grain boundaries, see figure 1. The resistivity, mobility, and free-carrier concentration in monocrystalline silicon vary with doping concentration of the single crystal silicon. Whereas the doping of polycrystalline silicon does have an effect on the resistivity, mobility, and free-carrier concentration, these properties strongly depend on the polycrystalline grain size, which is a physical parameter that the material scientist can manipulate. Through the methods of crystallization to form polycrystalline silicon, an engineer can control the size of the polycrystalline grains which will vary the physical properties of the material. The use of polycrystalline silicon in the production of solar cells requires