Nanoscale selective area growth of thick, dense, uniform, In-rich, InGaN nanostructure arrays on GaN/sapphire template

Abstract

Uniform, dense, single-phase, 150 nm thick indium gallium nitride (InGaN) nanostructure (nanorods and nanostripes) arrays have been obtained on gallium nitride templates, by metal organic chemical vapor deposition and nanoscale selective area growth on silicon dioxide patterned masks. The 150 nm thick InGaN nanorods have a perfect hexagonal pyramid shape with relatively homogenous indium concentration up to 22%, which is almost twice as high as in planar InGaN grown in the same condition, and luminesce at 535 nm. InGaN nanostripes feature c-axis oriented InGaN in the core which is covered by InGaN grown along semi-polar facets with higher In content. Transmission electron microscope and sub micron beam X-rays diffraction investigations confirm that both InGaN nanostructures are mostly defect free and monocrystalline. The ability to grow defect-free thick InGaN nanostructures with reduced polarization and high indium incorporation offers a solution to develop high efficiency InGaN-based solar cells. V

Nanoselective area growth of GaN by metalorganic vapor phase epitaxy on 4H-SiC using epitaxial graphene as a mask

“…2, in the shape of equilateraltriangle nanomesas with no nucleation on the epitaxial graphene. We find that the GaN nanostructures on SiC are significantly different from the typical hexagonal nanopyramids and their six (1101) or (1102) r-plane facets 12,13,19,20 . Here we use to our advantage the nonwetting property of graphene.…”

“…The very first layers of growth are cubic, as evidenced by their triangular faceting, which indicate a non-hexagonal symmetry: in-deed they do not grow as six-faceted nanopyramids as in Refs. 12,13,19,20 . The very good uniformity of all the GaN nanomesas and the absence of threading dislocation emerging from the interface with SiC are all apparent.…”

“…Heteroepitaxial nano selective area growth 12,17,18 (NSAG) was shown to alleviate these problems and produce high-quality and thick InGaN and GaN crystals. InGaN and GaN nanopya) Electronic mail: renaudpuybaret@gmail.com b) Electronic mail: claire.berger@physics.gatech.edu c) Electronic mail: aougazza@georgiatech-metz.fr ramids, with thickness over 100 nm and with no defects have been consistently grown with high throughput on various substrates, including silicon 13,19,20 . Difficulty with NSAG come from the additional processing steps required to pattern the mask and remove it after the nitride growth, and to implement the device back electrodes 7,[21][22][23] .…”

Investigation of new approaches for InGaN growth with high indium content for CPV application

“…For the second set of samples, nano-patterned substrates were fabricated on n-doped 2m thick c-oriented GaN/sapphire template following a procedure described in Ref. [8]. First, a 100 nm thick negative-tone resist (hydrogen silsesquioxane, HSQ) is spin-coated on the template.…”

“…This approach allows the elimination of the preexisting dislocations in the underlying template [7]. It also allows strain relaxation of InGaN layers without any dislocations, leading to higher In incorporation [8] and reduced piezo-electric effect. …”