Nanophotonic Devices Based on ZnO Nanowires

Abstract

ZnO nanowires (NWs) have attracted a great deal of interest because of their unique semiconducting, piezoelectric, biocompatibility, and optoelectronic properties, which are the fundamentals for their applications in electronics, photonics, biology, environmental science, and energy [1–3]. The attractive features of ZnO for photonic applications include its wide bandgap (3.37 eV), high exciton binding energy (60 meV), relatively high refractive index (n > 2 at visible spectral range), and several other manufacturing advantages of ZnO, including the availability of large area substrates at a relatively low cost, amenability to wet chemical etching, great tolerance to high-energy radiation, and long-term stability. Additionally, ZnO exhibits the most splendid and abundant configurations of nanostructures that one material can form. ZnO nanostructures can be grown by a variety of methods, especially by low-cost and low-temperature methods. They have great potential for a variety of photonic technological applications, such as optical interconnect [4, 5], ultraviolet laser [5–9], photodetector [10–15], dye-sensitized solar cell (DSSC) [16–20], and light-emitting diode (LED) [21–26], as shown in Fig. 12.1. Furthermore, because ZnO is also a piezoelectric material, the coupling of optical, mechanical, and electrical properties of ZnO NW provides new opportunities for fabricating functional devices [3, 27–29], aiming at improving the performance of optoelectronic devices [28, 29] and providing an effective method to integrate optomechanical devices with microelectronic systems [27].