The invention provides methods for growing an array of elongated nanostructures projecting from a surface. The nanostructures of the array are aligned substantially perpendicularly to the surface. In one aspect of the invention, the diameter of the nanostructures is between 10 nm and 200 nm. The methods of the invention can produce nanostructure growth at temperatures less than 350 degrees Celsius. Alignment of the nanostructures does not rely on epitaxial growth from a single crystal substrate, allowing a variety of substrates to be used.
ACKNOWLEDGEMENT OF GOVERNMENT SUPPORT
 This invention was made with Government support under Contract Number DEFG02-91-ER45439 awarded by the U.S. Department of Energy (DOE). The Government has certain rights in the invention.