Selective Area Growth of III- Nitride Nanorods on polar, semi-polar and non-polar orientations: Device applications

Abstract

The aim of this work is to provide an overview on the recent advances in the selective area growth of (In)GaN nanostructures by plasma assisted molecular beam epitaxy, focusing on their potential as building blocks for next generation light emitting diodes. The first two sections deal with the emission control in the entire ultraviolet to infrared range, including approaches for white light emission, using thick InGaN segments on axial nanocolumns. Selective area growth of axial nanostructures is developed on both GaN/sapphire templates and GaN-buffered Si(lll). Ordered arrays of InGaN/GaN light emitting diodes grown by molecular beam epitaxy, emitting in the blue (441 nm), green (502 nm), and yellow (568 nm) spectral range are reported. As an alternative to axial nanocolumns, section 3 reports on the growth and characterization of InGaN/GaN core-shell structures on an ordered array of top-down patterned GaN microrods. Finally, section 4 reports on the selective area growth of GaN, with and without InGaN insertion, on semi-polar (11-22) and non-polar (11-20) templates. Upon selective area growth the high defect density present in the semi-polar templates is strongly reduced as indicated by a dramatic improvement of the optical properties. In the case of selective area growth on non-polar (11-20) templates, the formation of nanostructures with a low aspect ratio took place allowing for the fabrication of high-quality, non-polar GaN pseudo-templates by coalescence of these nanostructures.