FANG ET AL. VOL. XXX ’ NO. XX ’ 000–000 ’ XXXX A www.acsnano.org Fabrication of Patterned Polymer Nanowire Arrays Hao Fang, †,‡ Dajun Yuan, § Rui Guo, § Su Zhang, ‡ Ray P. S. Han, † Suman Das, § and Zhong Lin Wang ‡, * † Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871, People's Republic of China, ‡ School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA, and § Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA O ne-dimensional nanomaterial de- vices of inorganic semiconductors and functional oxides have been studied for application in electrics, me- chanics, photonics, bioscience, and energy science. 1-9 Fabrication of patterned inor- ganic nanowires (NW) has been widely de- veloped via different methods, such as electron beam lithography (EBL), 10 nanoim- print lithography (NIL), 11,12 and nanosphere lithography (NSL). 13-15 Polymer-based NWs have been fabricated and demonstrated for applications in areas such as organic light- emitting diodes (OLED), field-effect transistors (FET), sensors, and organic solar cells. 16-19 Demonstrated approaches for the fabrica- tion of organic NWs include EBL, electro- chemical deposition, and anodic aluminum oxide (AAO). 20-22 However none of these ap- proaches provide a reliable, high-throughput, and low-cost solution for large-scale fabrica- tion of patterned organic NW arrays at a level required for industrial applications. We have previously demonstrated a fab- rication method using a single-step induc- tively coupled plasma (ICP) etching to get wafer-scale aligned NW arrays from com- mercial polymer films and functional organic materials, such as PMMA (poly(methyl methacrylate)), PS (polystyrene), PDMS (polydimethylsiloxane), PET (polyethylene terephthalate), PEDOT/PSS (poly(3,4-ethyle- nedioxythiophene)poly(styrenesulfonate)), and MEH-PPV (poly[2-methoxy-5-(2-ethylh- exyloxy)-1,4-phenylenevinylene]). 23 The density and length of NWs can be easily controlled via different thicknesses of de- posited gold and the etching time. 24 How- ever an ordered, period controllable NW array is still needed for further applications of functional devices such as OLEDs, OFETs, and solar cells. 25-27 Laser interference patterning (LIP) is known as a reliable and fast technique to achieve large-area periodic patterns and can be used to form an initial pattern on polymer films. 28-30 In this paper, we com- bine the pattern generating technology by LIP and ICP etching to fabricate ordered and large-scale polymer NW arrays with high- throughput on both UV-absorbent poly- mers including PET and Dura film (76% PE (polyethylene) (76%) and polycarbonate (24%)) and UV-transparent polymers such as PVA (polyvinyl acetate) and PP (polypropylene). The NW arrays can be fabricated after a short ICP etching of periodic patterns produced through LIP. RESULTS AND DISCUSSION Details about the LIP technique have been introduced previously. 29,30 Briefly, the interference period (P d ) is determined by the wavelength (λ) and the angle (θ) and is given by P d = λ/2 sin(θ/2). In the LIP experiments described here, the laser wave- length is 266 nm. By changing the angle between two laser beams, the period can be easily changed from approximately λ/2 to several hundreds of micrometers. The ex- posure dose is another important experimen- tal parameter. By increasing the exposure dose, both the width and the depth of the ARTICLE *Address correspondence to zlwang@gatech.edu. Received for review December 5, 2010 and accepted December 22, 2010 Published online 10.1021/nn103319p C XXXX American Chemical Society ABSTRACT A method for the large-scale fabrication of patterned organic nanowire (NW) arrays is demonstrated by the use of laser interference patterning (LIP) in conjunction with inductively coupled plasma (ICP) etching. The NW arrays can be fabricated after a short ICP etching of periodic patterns produced through LIP. Arrays of NWs have been fabricated in UV-absorbent polymers, such as PET (polyethylene terephthalate) and Dura film (76% polyethylene and 24% polycarbonate), through laser interference photon ablation and in UV transparent polymers such as PVA (polyvinyl acetate) and PP (polypropylene) through laser interference lithography of a thin layer of photoresist coated atop the polymer surface. The dependence of the structure and morphology of NWs as a function of initial pattern created by LIP and the laser energy dose in LIP is discussed. The absence of residual photoresist atop the NWs in UV-transparent polymers is confirmed through Raman spectroscopy. KEYWORDS: organic nanowire arrays • laser interference patterning