Masashi Nakao

Highly ordered nanochannel-array architecture in anodic alumina

The development of the ordered channel array in the anodic porous alumina was initiated by the textured pattern of the surface made by the molding process, and growth of an almost defect-free channel array can be achieved throughout the textured area. The long-range-ordered channel array with dimensions on the order of millimeters with a channel density of 1010u2002cm−2 was obtained, and the aspect ratio was over 150. The master for molding could be used many times, which makes it possible to overcome problems in the conventional nanolithographic technique, such as low through-put and high cost.

Nanoimprint technology for application to photonic devices

We have developed nanoimprint technology to fabricate functional optical components. The future and usage of various molds for nanoimprint are described and their patterning examples are shown. Several applications of the nanoimprint technology are introduced; anti-reflection surface structure by using graded convex and concave patterns, extremely low threshold dye laser by 2-dimensional photonic crystals infiltrated with a gain medium, and various semiconductor nanostructures being used for functional optical devices. Nanoimprint is key technology to realize these components.

Direct measurement of size fluctuation in reverse‐mesa etched quantum wire structures by the atomic force microscope

By means of atomic force microscopy, we have directly measured, for the first time, size fluctuations in InGaAs/InP quantum wire structures fabricated by e‐beam lithography and reverse‐mesa wet etching. Based on a statistical analysis of the measured data, we discuss the standard deviation of the lateral size of wire structures. The results clearly indicate that the size fluctuations in the wire patterns are predominantly small compared to those in the original mask patterns. This is attributed to the formation of crystallographic facet during the reverse‐mesa wet etching.