Polarity‐ and Site‐Controlled Metal Organic Vapor Phase Epitaxy of 3D‐GaN on Si(111)

Abstract

A site‐ and polarity‐controlled MOVPE growth of 3D‐GaN on Si(111) substrates is established using the polarity‐dependent growth speed of GaN on an intermediate AlN layer. For hydrogenated Si or elevated AlN growth temperatures mixed‐polar growth is observed. N‐polarity could be realized on oxidized Si(111) surfaces by a reduced AlN growth temperature of TAlN = 930 °C. Specific Si crystal facets (e.g., {100}, {112¯}) are determined as starting points for metal‐polar growth of AlN. By site‐controlled etching in Si, we intentionally expose these additional crystal facets prior to epitaxy to obtain defined starting points for metal‐polar growth. At TAlN = 930 °C, this leads to a site‐controlled growth of metal‐polar GaN, surrounded by N‐polar AlN on Si(111). Thus both, a polarity‐ and site‐controlled epitaxial growth of 3D‐GaN is achieved. The new developed method has been applied to a large variety of structure sizes from 650 nm to 1 mm. The results are supported by a schematic model, explaining the influence of surface termination, in situ desorption, and growth conditions. This paves the way to the development of future 3D‐opto‐electronic devices, directly established on Si.

Progress and Challenges of InGaN/GaN-Based Core–Shell Microrod LEDs

“…Additionally, the direct growth of GaN on Si(111) is not possible due to the Ga melt-back etching effect. An AlN buffer layer on Si-pillars can help to control the surface polarity of the microrods and reduce the Ga melt-back etching effect [27,28]. The polarity can be controlled by the growth substrate and/or different buffer layers.…”

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

“…As the Si substrate is nonpolar, resultant growth of AlN or GaN can be of either polarity, and mixed polarity nanowires are also observed. [16][17][18]34,35 The nanowires with mixed polarity will contain inversion domain boundaries (IDB) separating domains of Ga and N polarity as reported in refs 19 and 36. Inversion domains have been reported to originate from eutectic Al−Si reactions for Si (111) substrates.…”