Selective-area growth of GaN nanowires on SiO2-masked Si (111) substrates by molecular beam epitaxy

Abstract

We analyze a method to selectively grow straight, vertical gallium nitride nanowires by plasma-assisted molecular beam epitaxy (MBE) at sites specified by a silicon oxide mask, which is thermally grown on silicon (111) substrates and patterned by electron-beam lithography and reactive-ion etching. The investigated method requires only one single molecular beam epitaxy MBE growth process, i.e., the SiO2 mask is formed on silicon instead of on a previously grown GaN or AlN buffer layer. We present a systematic and analytical study involving various mask patterns, characterization by scanning electron microscopy, transmission electron microscopy, and photoluminescence spectroscopy, as well as numerical simulations, to evaluate how the dimensions (window diameter and spacing) of the mask affect the distribution of the nanowires, their morphology, and alignment, as well as their photonic properties. Capabilities and limitations for this method of selective-area growth of nanowires have been identified. A window diameter less than 50 nm and a window spacing larger than 500 nm can provide single nanowire nucleation in nearly all mask windows. The results are consistent with a Ga diffusion length on the silicon dioxide surface in the order of approximately 1 μm.

Emerging Applications of III‐Nitride Nanocrystals

“…[31][32][33] Since then, III-nitride nanocrystals, also commonly referred to as nanowires, or nanorods, have been intensively studied. [21,[34][35][36][37][38][39][40][41][42][43][44] They have emerged as unique platform, not only for materials studies but also for many practical device applications, including LEDs, lasers, photodetectors, transistors, solar cells, and artificial photosynthesis, to name just a few.…”

In(Ga)N Nanostructures and Devices Grown by Molecular Beam Epitaxy and Metal-Assisted Photochemical Etching

“…When the diameter of the mask window was less than 50 nm, most of the NWs were straight and vertical. The diffusion length was also influenced by the window spacing; when the spacing exceeded 1 μm, the ratio of window space to unoccupied window space was almost unrelated to the window density [ 123 ].…”

Light-Emitting Diodes Based on InGaN/GaN Nanowires on Microsphere-Lithography-Patterned Si Substrates

“…According to the SEM images, the patterned SiO 2 layers enabled the selective MBE growth of NWs in every hole of the mask. Note that the chosen MBE regime provided the nucleation and growth of both vertically aligned NWs and tripod nanostructures, which can be caused by an insufficiently high growth temperature or by the features of NW nucleation in the holes of the mask [36,37]. One can also note that the decreased temperature-required for the NW active area and shell formation-enabled the nucleation of a 2D parasitic layer on the surface of the SiO 2 mask.…”