Catalyst-free GaN Nanowire Growth and Optoelectronic Characterization

摘要

We discuss the present state-of-the-art concerning the growth mechanism, optical luminescence and electrical properties for GaN nanowires grown with catalyst-free molecular beam epitaxy. These nanowires are essentially defect-free and display long photoluminescence lifetimes and carrier mobilities relative to epitaxially grown GaN films. The exclusion of crystalline defects comes from the ease with which strain-relieving dislocations can reach the sidewalls and terminate. The growth mechanism is based on variations in Ga sticking coefficients and surface energies of the sidewall planes and end facet planes. With control of the nucleation process through selective epitaxy on patterned substrates, a high degree of diameter, length and position control can be achieved. Common difficulties with interpretation of optical and electrical data with regard to internal quantum efficiency and mobility are also addressed.