A method of preparing nanorod arrays using ion beam implantation is described that includes defining a pattern on a substrate and then implanting ions into the substrate using ion beam implantation. Next, a thin film is deposited on the substrate. During film growth, nanotrenches form and catalyze the formation of nanorods through capillary condensation. The resulting nanorods are aligned with the supporting matrix and are free from lattice and thermal strain effect. The density, size, and aspect ratios of the nanorods can be varied by changing the ion beam implantation and thin film growth conditions resulting in control of emission efficiency.
 The U.S. Government has a paid-up license in this invention, and the right, in limited circumstances, to require the patent owner to license others on reasonable terms as provided for by the terms of the Department of Energy Grant No. DE-FG02-05ER46208 and the National Science Foundation (NSF) Grant No. DMR-0404542.