Nicholas Morgan

École Polytechnique Fédérale de Lausanne

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Anna Fontcuberta i Morral

École Polytechnique Fédérale de Lausanne

Didem Dede

École Polytechnique Fédérale de Lausanne

Valerio Piazza

École Polytechnique Fédérale de Lausanne

Akshay Balgarkashi

École Polytechnique Fédérale de Lausanne

Lucas Güniat

École Polytechnique Fédérale de Lausanne

Martin Friedl

École Polytechnique Fédérale de Lausanne

Jean-Baptiste Leran

École Polytechnique Fédérale de Lausanne

Wonjong Kim

Pohang University of Science and Technology

Nicolas Tappy

École Polytechnique Fédérale de Lausanne

ВГ

В. Г. Дубровский

St Petersburg University

Cooperative Institutions

École Polytechnique Fédérale de Lausanne

Centre National de la Recherche Scientifique

Laboratoire des Matériaux Avancés

Lund University

Instituto de Ciencia de Materiales de Sevilla

University of Oxford

Engineering (Italy)

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University of Basel

Consejo Superior de Investigaciones Científicas

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The implementation of thermal and UV nanoimprint lithography for selective area epitaxy

Nanotechnology (2023)

Antonia Hager Lucas Güniat Nicholas Morgan Santhanu Panikar Ramanandan A. Rudra

Abstract Semiconductor nanowires (NWs) in horizontal configuration could provide a path for scalable NW-based devices. Bottom–up large-scale manufacturing of these nanostructures by selective area epitaxy (SAE) relies on precise nanopatterning of various shapes on the growth masks. Electron beam lithography offers an extraordinary accuracy suited for the purpose. However, this technique is not economically viable for large production as it has a low throughput and requires high investment and operational costs. Nanoimprint lithography (NIL) has the potential to reduce fabrication time and costs significantly while requiring less sophisticated equipment. In this work, we utilize both thermal and UV NIL for patterning substrates for SAE, elucidating the advantages and disadvantages of each lithography technique. We demonstrate the epitaxial growth of Ge and GaAs NWs on these substrates, where we observe high-quality mono-crystalline structures. Even though both processes can produce small uniform structures suitable for SAE, our results show that UV NIL proves to be superior and enables reliable and efficient patterning of sub-100 nm mask features at the wafer scale.

Nanoimprint lithography

Next-generation lithography

Stencil lithography

10.1088/1361-6528/acea87

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Nanoscale Mapping of Light Emission in Nanospade-Based InGaAs Quantum Wells Integrated on Si(100): Implications for Dual Light-Emitting Devices

ACS Applied Nano Materials (2022)

Lucas Güniat Nicolas Tappy Akshay Balgarkashi Titouan Charvin Raphaël Lemerle

III-V semiconductors outperform Si in many optoelectronics applications due to their high carrier mobility, efficient light emission and absorption processes, and the possibility to engineer their band gap through alloying. However, complementing Si technology with III-V semiconductors by integration on Si(100) remains a challenge still today. Vertical nanospades (NSPDs) are quasi-bi-crystal III-V nanostructures that grow on Si(100). Here, we showcase the potential of these structures in optoelectronics application by demonstrating InGaAs heterostructures on GaAs NSPDs that exhibit bright emission in the near-infrared region. Using cathodoluminescence hyperspectral imaging, we are able to study light emission properties at a few nanometers of spatial resolution, well below the optical diffraction limit. We observe a symmetric spatial luminescence splitting throughout the NSPD. We correlate this characteristic to the structure's crystal nature, thus opening new perspectives for dual wavelength light-emitting diode structures. This work paves the path for integrating optically active III-V structures on the Si(100) platform.

Cathodoluminescence

Light emission

10.1021/acsanm.2c00507

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Scalable Receivers Based on Horizontally-grown InAs Nanowires Promise All-fiber Terahertz Spectrometer Systems

2022 47th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz) (2024)

Kun Peng Nicholas Morgan Ford M. Wagner Thomas Siday Chelsea Q. Xia

10.1109/irmmw-thz60956.2024.10697914

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From Layer-by-Layer Growth to Nanoridge Formation: Selective Area Epitaxy of GaAs by MOVPE

Crystal Growth & Design (2023)

Nicholas Morgan В. Г. Дубровский Ann-Kristin Stief Didem Dede Marie Sanglé-Ferrière

Selective area epitaxy at the nanoscale enables fabrication of high-quality nanostructures in regular arrays with predefined geometry. Here, we investigate the growth mechanisms of GaAs nanoridges on GaAs (100) substrates in selective area trenches by metal-organic vapor-phase epitaxy (MOVPE). It is found that pre-growth annealing results in the formation of valley-like structures of GaAs with atomic terraces inside the trenches. MOVPE growth of GaAs nanoridges consists of three distinct stages. Filling the trench in the first stage exhibits a step-flow growth behavior. Once the structure grows above the mask surface, it enters the second stage of growth by forming {101} side facets as the (100) flat top facet progressively shrinks. In the third stage, the fully formed nanoridge begins to overgrow onto the mask with a significantly reduced growth rate. We develop a kinetic model that accurately describes the width-dependent evolution of the nanoridge morphology through all three stages. MOVPE growth of fully formed nanoridges takes only about 1 min, which is 60 times faster than in our set of molecular beam epitaxy (MBE) experiments reported recently, and with a more regular, triangular cross-sectional geometry defined solely by the {101} facets. In contrast to MBE, no material loss due to Ga adatom diffusion onto the mask surface is observed in MOVPE until the third stage of growth. These results are useful for the fabrication of GaAs nanoridges of different dimensions on the same substrate for various applications and can be extended to other material systems.

10.1021/acs.cgd.3c00316

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Citations (9)

Accompanying dataset to ACS Appl. Nano Mater. 2022, 5, 4, 5508–5515 : Nanoscale Mapping of Light Emission in Nanospade-Based InGaAs Quantum Wells Integrated on Si(100): Implications for Dual Light-Emitting Devices

Zenodo (CERN European Organization for Nuclear Research) (2022)

Lucas Gueniat Nicolas Tappy Akshay Balgarkashi Titouan Charvin Raphaël Lemerle

Accompanying dataset containing the raw data and analysis contained in the main publication. This comprises the fitted CL-SEM dataset, the CL-STEM dataset, the CL-SEM presented in the SI and the STEM-EDX linescans.

10.5281/zenodo.6793319

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Fabrication of Single‐Crystalline InSb‐on‐Insulator by Rapid Melt Growth

physica status solidi (a) (2021)

Heera Menon Nicholas Morgan Crispin Hetherington Robin Athle Matthew J. Steer

InSb has the smallest bandgap and highest electron mobility among III‐V semiconductors and is widely used for photodetectors and high‐frequency electronic applications. Integration of InSb directly on Si would drastically reduce the fabrication cost and enable new applications, however, it is very challenging due to its 19% lattice mismatch with Si. Herein, the integration of single‐crystalline InSb microstructures on insulator‐covered Si through rapid melt growth (RMG) is reported and specifically provides details on the fabrication process. The importance of achieving high‐quality conformal capping layers at low thermal budget to contain the InSb melt is assessed when the sample is annealed. The importance of ensuring a pristine Si seed area to achieve single‐crystalline InSb is illustrated and demonstrated here for the first time.

10.1002/pssa.202100467

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Fabrication and Testing of Flexible Pulsating Heat Pipes

Nicholas Morgan Damian Hundley Maya Baron Matthew Pichardo Shawn A. Putnam

The demand for flexible microelectronics has increased significantly within the last decade. This study investigates the cooling performance of flexible pulsating heat pipes (PHPs) made from acrylic with a bend radius of ≈300 mm. The fabricated devices support two-phase, pulsating fluid flow inside the rectangular microchannels. Both water and ethanol are used as coolants, where local hot spots are generated by cobalt-alloy foil heaters inside the flexible PHPs. The PHP's dissipate the heat generated to the environment via copper condensers with controlled setpoint temperatures. Based on a heater surface area of ≈1.5 cm ² and a condenser setpoint temperature of 25°C, the maximum heat flux observed for sustained and repeatable cooling with water and ethanol was 8 W /cm ² . These heat fluxes correlate well with other PHP studies with similar heater power loads, channel geometries, and coolants.

Condenser (optics)

Set point

Microelectronics

10.1109/itherm55368.2023.10177672

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Coherent Hole Transport in Selective Area Grown Ge Nanowire Networks

Nano Letters (2022)

Santhanu Panikar Ramanandan Petar Tomić Nicholas Morgan Andrea Giunto A. Rudra

Holes in germanium nanowires have emerged as a realistic platform for quantum computing based on spin qubit logic. On top of the large spin-orbit coupling that allows fast qubit operation, nanowire geometry and orientation can be tuned to cancel out charge noise and hyperfine interaction. Here, we demonstrate a scalable approach to synthesize and organize Ge nanowires on silicon (100)-oriented substrates. Germanium nanowire networks are obtained by selectively growing on nanopatterned slits in a metalorganic vapor phase epitaxy system. Low-temperature electronic transport measurements are performed on nanowire Hall bar devices revealing high hole doping of ∼1018 cm-3 and mean free path of ∼10 nm. Quantum diffusive transport phenomena, universal conductance fluctuations, and weak antilocalization are revealed through magneto transport measurements yielding a coherence and a spin-orbit length of the order of 100 and 10 nm, respectively.

Spin–orbit interaction

10.1021/acs.nanolett.2c00358

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Low Dimensional III-V and II-VI Semiconductors

Microscopy and Microanalysis (2022)

Didem Dede Nicholas Morgan Nadine Gächter Timur Nurmamytov Marta De Luca

Journal Article Low Dimensional III-V and II-VI Semiconductors Get access Didem Dede, Didem Dede École Polytechnique Fédérale de Lausanne. Search for other works by this author on: Oxford Academic Google Scholar Nicholas Morgan, Nicholas Morgan École Polytechnique Fédérale de Lausanne. Search for other works by this author on: Oxford Academic Google Scholar Nadine Gächter, Nadine Gächter University of Basel. Search for other works by this author on: Oxford Academic Google Scholar Timur Nurmamytov, Timur Nurmamytov Istituto Officina dei Materiali CNR, Trieste, Italy Search for other works by this author on: Oxford Academic Google Scholar Marta De Luca, Marta De Luca University of Basel.Sapienza Università di Roma. Search for other works by this author on: Oxford Academic Google Scholar Silvia Rubini, Silvia Rubini Istituto Officina dei Materiali CNR, Trieste, Italy Search for other works by this author on: Oxford Academic Google Scholar Anna Fontcuberta i Morral Anna Fontcuberta i Morral École Polytechnique Fédérale de Lausanne. Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 28, Issue S1, 1 August 2022, Page 2004, https://doi.org/10.1017/S1431927622007784 Published: 01 August 2022

10.1017/s1431927622007784

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Zenodo (CERN European Organization for Nuclear Research) (2022)

Lucas Gueniat Nicolas Tappy Akshay Balgarkashi Titouan Charvin Raphaël Lemerle

Light emission

10.5281/zenodo.6793320

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