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Hexagonal Nanopyramidal Prisms of Nearly Intrinsic InN on Patterned GaN Nanowire Arrays

Crystal Growth and Design

Golam Sarwar, A.T.M.; Leung, Benjamin; Wang, George T.; Myers, Roberto C.

By using multiple growth steps that separate the nucleation and growth processes, we show that nearly intrinsic InN single nanocrystals of high optical quality can be formed on patterned GaN nanowire arrays by molecular beam epitaxy. The InN nanostructures form into well-defined hexagonal prisms with pyramidal tops. Micro-photoluminescence (μ-PL) is carried out at low temperature (LT: 28.2 K) and room temperature (RT: 285 K) to gauge the relative material quality of the InN nanostructures. Nanopyramidal prisms grown using a three-step growth method are found to show superior quantum efficiency. Excitation and temperature dependent μ-PL demonstrates the very high quality and nearly intrinsic nature of the ordered InN nanostructure arrays.

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TYPE Journal Article YEAR 2018
DOIDOIOSTIScopusOSTIScopus

Visible Quantum Nanophotonics

Subramania, Ganapathi S.; Wang, George T.; Fischer, Arthur J.; Wierer, Jonathan J.; Tsao, Jeffrey Y.; Koleske, Daniel K.; Coltrin, Michael E.; Agarwal, Sapan A.; Anderson, P.D.; Leung, Ben

The goal of this LDRD is to develop a quantum nanophotonics capability that will allow practical control over electron (hole) and photon confinement in more than one dimension. We plan to use quantum dots (QDs) to control electrons, and photonic crystals to control photons. InGaN QDs will be fabricated using quantum size control processes, and methods will be developed to add epitaxial layers for hole injection and surface passivation. We will also explore photonic crystal nanofabrication techniques using both additive and subtractive fabrication processes, which can tailor photonic crystal properties. These two efforts will be combined by incorporating the QDs into photonic crystal surface emitting lasers (PCSELs). Modeling will be performed using finite-different time-domain and gain analysis to optimize QD-PCSEL designs that balance laser performance with the ability to nano-fabricate structures. Finally, we will develop design rules for QD-PCSEL architectures, to understand their performance possibilities and limits.

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TYPE SAND Report YEAR 2017
DOIOSTIDOIOSTI

Nonpolar InGaN/GaN Core-Shell Single Nanowire Lasers

Nano Letters

Li, Changyi; Wright, Jeremy B.; Liu, Sheng L.; Lu, Ping L.; Figiel, J.J.; Leung, Benjamin; Chow, Weng W.; Brener, Igal B.; Koleske, Daniel K.; Luk, Ting S.; Feezell, Daniel F.; Brueck, S.R.J.; Wang, George T.

We report lasing from nonpolar p-i-n InGaN/GaN multi-quantum well core-shell single-nanowire lasers by optical pumping at room temperature. The nanowire lasers were fabricated using a hybrid approach consisting of a top-down two-step etch process followed by a bottom-up regrowth process, enabling precise geometrical control and high material gain and optical confinement. The modal gain spectra and the gain curves of the core-shell nanowire lasers were measured using micro-photoluminescence and analyzed using the Hakki-Paoli method. Significantly lower lasing thresholds due to high optical gain were measured compared to previously reported semipolar InGaN/GaN core-shell nanowires, despite significantly shorter cavity lengths and reduced active region volume. Mode simulations show that due to the core-shell architecture, annular-shaped modes have higher optical confinement than solid transverse modes. The results show the viability of this p-i-n nonpolar core-shell nanowire architecture, previously investigated for next-generation light-emitting diodes, as low-threshold, coherent UV-visible nanoscale light emitters, and open a route toward monolithic, integrable, electrically injected single-nanowire lasers operating at room temperature.

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TYPE Journal Article YEAR 2017
DOIOSTIScopus

Ultrafast Carrier Capture and Auger Recombination in Single GaN/InGaN Multiple Quantum Well Nanowires

ACS Photonics

Boubanga-Tombet, Stephane; Wright, Jeremy B.; Lu, Ping L.; Williams, Michael R.C.; Li, Changyi; Wang, George T.; Prasankumar, Rohit P.

Ultrafast optical microscopy is an important tool for examining fundamental phenomena in semiconductor nanowires with high temporal and spatial resolution. Here, we used this technique to study carrier dynamics in single GaN/InGaN core-shell nonpolar multiple quantum well nanowires. We find that intraband carrier-carrier scattering is the main channel governing carrier capture, while subsequent carrier relaxation is dominated by three-carrier Auger recombination at higher densities and bimolecular recombination at lower densities. The Auger constants in these nanowires are approximately 2 orders of magnitude lower than in planar InGaN multiple quantum wells, highlighting their potential for future light-emitting devices.

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TYPE Journal Article YEAR 2016
DOIOSTIScopus
Results 76–100 of 273
Results 76–100 of 273