CHARACTERISING NANOWIRE ARRAYS BY COMPUTER VISION BASED ON SEM IMAGES

摘要

Nanowires for optoelectronic devices are now commonly grown in ordered arrays to ensure uniform growth conditions [1]. With arrays of hundreds or thousands of individual nanowires, there is a need for high-volume nanoscale analysis. This work explores the effect of patterning growth substrates to achieve uniform nanowire growth. Patterning is demonstrated with focussed ion beam (FIB) milled hole arrays [2] as well as large-area patterning by nanoimprint lithography [3]. The evaluation of more than 50,000 nanowires is made possible with the development of a computer vision-based analysis of scanning electron microscopy (SEM) images. Automating the analysis of significant numbers of nanowires gives unique insight into the final effect of substrate patterning parameters for the two different methods. For example, the yield of single vertical nanowires in FIB-patterned arrays can be easily calculated on an array-to-array basis. Likewise, the uniformity in nanowire size over large areas can be calculated for NIL patterned growth substrates.