InAs nanowires grown by metal-organic vapor-phase epitaxy (MOVPE) employing PS/PMMA diblock copolymer nanopatterning

Dense arrays of indium arsenide (InAs) nanowire materials have been grown by selective-area metal-organic vapor-phase epitaxy (SA-MOVPE) using polystyrene-b-poly(methyl methacrylate) (PS/PMMA) diblock copolymer (DBC) nanopatterning technique, which is a catalyst-free approach. Nanoscale openings were defined in a thin (∼10 nm) SiN_x layer deposited on a (111)B-oriented GaAs substrate using the DBC process and CF₄ reactive ion etching (RIE), which served as a hard mask for the nanowire growth. InAs nanowires with diameters down to ∼20 nm and micrometer-scale lengths were achieved with a density of ∼5 × 10¹⁰ cm². The nanowire structures were characterized by scanning electron microscopy and transmission electron microscopy, which indicate twin defects in a primary zincblende crystal structure and the absence of threading dislocation within the imaged regions.