Polarity dependent strongly inhomogeneous In-incorporation in GaN nanocolumns

Abstract

In this work, GaN/InGaN/GaN nanocolumns (NCs) have been grown by molecular beam epitaxy. Selective area growth (SAG) and self-organized growth (SOG) were performed simultaneously in patterned and unpatterned regions of the same substrate, respectively. The resulting structures show different tip morphologies and structural properties due to the different polarity along the growth direction, namely Ga-polar with r-plane faceted tips for the SAG NCs and N-polar with c-plane top facet for the SOG ones. When growing Ga-polar GaN/InGaN NCs, no indium is incorporated at a substrate temperature of [Formula: see text]°C. Rather, indium incorporation takes place under the same growth conditions on the N-polar NCs. The In-incorporation is investigated by means of nano x-ray fluorescence and diffraction, high-angle annular dark-field scanning transmission electron microscopy and high-resolution transmission electron microscopy.

Silane-Induced N-Polarity in Wires Probed by a Synchrotron Nanobeam

“…The authors found the driving force for indium surface segregation to be stronger in the case of Ga-face polarity. Likewise, a strong polarity dependent inhomogeneous In-incorporation has been experimentally encountered in GaN nanocolumns grown by MBE . Although InGaN/GaN MQWs are also deposited on the n upper segment of the GaN wire, our findings suggest that In incorporation at the top of the structure seems to be easier on N-polar GaN (n ++ Si-doped segments) than on Ga-polar GaN, as reported by Nath et al., who provided experimental evidence of such effect in epitaxial layers.…”

Free-Standing InAs Nanobelts Driven by Polarity in MBE

“…Moreover, individual low-dimensional nanostructures such as nanosheets and nanobelts with a large area/thickness ratio can also be applied in fields such as spintronics and topological quantum computing . Additionally, it has been found that polarity plays a crucial role in the III–V nanowire growth, which can influence crystal quality, morphology, compositional distribution, and growth direction. − Therefore, the polarity-driven effect can be a potential approach towards creating novel III–V nanostructures.…”

Determining GaN Nanowire Polarity and its Influence on Light Emission in the Scanning Electron Microscope

“…While the majority of GaN structures have Ga-polar surfaces, N-polar surfaces offer a great advantage for high electron mobility transistors providing a strong back barrier layer, low resistivity Ohmic contacts and improved capability for large scale device processing . Recently there has been immense interest in determining polarity in semiconductor based nanowires in order to better understand their polarity dependent growth mechanisms. − In some cases the polarity also determines the final shape of the nanowires and can also be engineered to form new nanostructures …”