ABSTRACT
In the past decade, tremendous progress has been made in the growth/synthesis and characterization of III-nitride nanowires, including InN, GaN, AlN, and their alloys (Bertness et al. 2010; Lin et al. 2010; Hestroffer et al. 2011; Jenichen et al. 2011; Waag et al. 2011; González-Posada et al. 2012; Albert et al. 2013; Jahangir et al. 2013; Katsumi et al. 2013; Nguyen et al. 2013; Sarwar et al. 2015b; Zhao et al. 2016). Compared to their conventional planar counterparts, nearly dislocation and strain-free III-nitride nanowires can be epitaxially grown on Si, sapphire, SiO x and other foreign substrates, due to the efficient strain relaxation associated with the large surface-to-volume ratio (Zhao et al. 2013a). Moreover, recent studies, both theoretically and experimentally, have shown that the group III substitutional Mg-doping has significantly lower surface formation energy compared to that in the bulk region (Zhao et al. 2013b; Zhao et al. 2015a), thereby leading to enhanced dopant incorporation and efficient p-type conduction that is often difficult to achieve in III-nitride planar structures. It has been shown that the room-temperature emission wavelengths of III-nitride nanowires can be tuned from the deep ultraviolet (UV) (~207 nm for AlN), through the deep visible, to the near-infrared spectral range (~1.9 µm for InN) by varying the alloy compositions (Wu 2009; César et al. 2011). Recently, it has also been discovered that III-nitrides are the only 244semiconductors whose energy band edges can straddle water redox potentials under deep visible and even possibly near-infrared light irradiation, which is essential for the efficient generation of solar fuels through water splitting and CO2 reduction (Moses et al. 2010; Kibria et al. 2016b).
