Nanoimprint assisted transfer of different density vertically aligned ZnO nanorod arrays

Abstract

The method developed for transferring vertically aligned ZnO nanorod arrays onto arbitrary substrates is highly desirable for the fabrication of ZnO based electronic devices. In this study, vertically aligned ZnO nanorod arrays of different densities were prepared on Al₂O₃ (0001) substrate by electron beam lithography, combined with the hydrothermal method. The aspect ratio of ZnO nanorod arrays was adjusted by varying the precursor concentration, reaction time, reaction temperature and addition of polyethyleneimine (PEI) molecules in the hydrothermal process. In the following transferring stage, the hot nanoimprint technique was performed, which enabled the ZnO nanorod arrays to easily penetrate into the PMMA transferred layers, while maintaining the integrity and fidelity of the transferred rod arrays. As a result, different density ZnO nanorod arrays were successfully transferred from the donor substrate to ITO glass and more flexible plastic substrates. Furthermore, the surface state of ZnO nanorod arrays was effectively removed through forming Ag electrodes during the transfer process, and Ohmic contacts were successfully formed between the Ag electrodes and ZnO nanorod arrays, which was convenient for the fabrication of high efficiency nanodevices based on ZnO nanorod arrays.