Emission enhancement from nonpolar a-plane III-nitride nanopillar

Abstract

A nonpolar a-plane GaN-based light emitting structure was patterned by self-assembled SiO2 nanosphere lithography and subsequent inductively coupled plasma (ICP) etch to define an array of nanopillar light emitters. The photoluminescence (PL) intensity was enhanced by ∼110% after the anisotropic ICP etch, compared with an unprocessed sample, which is attributed to a reduction in wave-guiding effects in the thin film. Additionally, the anisotropic ICP etch caused minimal wavelength shift in the dominant 3.34 eV near-bandedge radiative transition. A subsequent photoelectrochemical (PEC) etch process of the a-plane GaN nanopillars preferentially etched the underlying n-type layers, leaving a wider p-type cap. The n-type layers wet-etched by recession of the N-polar (000-1) plane (perpendicular to the a-plane growth axis) via formation of the distinctive pyramid-shaped facets. The PL intensity was enhanced by ∼168% after ICP and PEC etching although the peak emission occurred at a lower energy. The combination of nanosphere lithography and ICP was highly effective in improving the light extraction efficiency in a-plane nonpolar GaN-based light emitting diodes.

III‐nitride nanowire based light emitting diodes on carbon paper

“…While the nanowires grow along the adirection, a small amount of deposition directly on the carbon paper presents a range of diffracting planes at the nominal surface. A 2θ-θ X-ray diffraction pattern in Figure 2 presents sharp diffraction from the (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) planes as well as weaker diffraction from other planes. Additional experiments demonstrated that the InGaN peak varied with the composition of the InGaN as expected.…”

“…[7][8][9][10][11][12][13][14] The standard fabrication utilizes an expense laden process to build a multi-layer thin-film structure on rigid substrates such as sapphire. [15][16][17][18][19][20][21][22][23][24][25][26] A contrasting application would be a lowemittance device covering a non-planar architectural structure, e.g., a pillar, or flexible element. To make such as device economically and mechanically feasible would require a lowcost process on a flexible substrate.…”

Improved performance of GaN-based light emitting diodes with nanopatterned sapphire substrates fabricated by wet chemical etching

“…19,20 Nanosphere lithography (NSL) technique, which is based on a monolayer-colloidal-crystal (MCC) templating strategy, has been employed as an economic way to construct largearea and highly ordered nanostructures, 21,22 which have demonstrated important applications in the optoelectronic devices. [23][24][25][26] Recently, NSL has been utilized to prepare NPSS with the advantage of large-area fabrication and flexible tuning of the feature size. [27][28][29][30][31] The fabrication of NPSS involves pattern defining and pattern transferring to the sapphire substrate.…”

Nickel Foam as a Substrate for III-nitride Nanowire Growth

“…Complex procedures such as die shaping, photonic crystals, micro-cavities, and surface roughening are used to extract light that would normally be trapped in the semiconductor and substrate slab. [14][15][16][17][18][19] Nanowire III-nitride light emitters have been suggested and demonstrated to avoid many of the deleterious issues associated with thin film structures. 20,21 The dimensions of the nanowire are on the order of the optical wavelength; therefore, light is easily scattered out of the semiconductor into the surrounding air.…”