Molecular Beam Epitaxial Growth of III-Nitride Nanowire Heterostructures and Emerging Device Applications
This chapter describes some of the major advances made by the molecular beam epitaxy (MBE) growth of III-nitride nanowire heterostructures, including InN, In-rich InGaN, AlN, and Al-rich AlGaN nanowires. To date, a large number of III-nitride nanowire structures by MBE are spontaneously formed through a self-organized process under nitrogen-rich conditions on Si substrate, driven by the anisotropy of various surface properties such as chemical potential and sticking coefficient. Electrical transport properties of such hexagonal InN nanowires have also been investigated by nano-probing technique. High-quality In-rich InGaN materials are essentially required for application in high-efficiency deep visible LEDs and lasers, multijunction photovoltaic devices, and solar fuel production. However, the epitaxy of In-rich InGaN alloys has remained challenging, due to the large lattice mismatch between InN and GaN and the lack of suitable substrates. The presence of surface states and defects in In-rich InGaN nanowires and the resulting nonradiative surface recombination generally lead to extremely short carrier lifetime in nanowire structures.