In-Situ Transmission Electron Microscopy Imaging of Aluminum Diffusion in Germanium Nanowires for the Fabrication of Sub-10 nm Ge Quantum Disks
| Autor: | Alois Lugstein, Masiar Sistani, Pascal Gentile, Minh Anh Luong, Eric Robin, B. Fernandez, M. den Hertog, N. Pauc, Maria Spies |
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| Přispěvatelé: | Laboratoire d'Etude des Matériaux par Microscopie Avancée (LEMMA ), Modélisation et Exploration des Matériaux (MEM), Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA)-Institut de Recherche Interdisciplinaire de Grenoble (IRIG), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Grenoble Alpes (UGA), Silicon Nanoelectronics Photonics and Structures (SiNaps), PHotonique, ELectronique et Ingénierie QuantiqueS (PHELIQS), Institute of Applied Physics [Vienna] (TU Wien), Vienna University of Technology (TU Wien), Matériaux, Rayonnements, Structure (NEEL - MRS), Institut Néel (NEEL), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Nanofabrication (NEEL - Nanofab), Austrian Science Fund (FWF): project no. P28175-N27, ANR-10-LABX-0051,LANEF,Laboratory of Alliances on Nanosciences - Energy for the Future(2010), European Project: 758385,e-See - H2020-EU.1.1. |
| Rok vydání: | 2020 |
| Předmět: |
In situ
Materials science in-situ transmission electron microscopy Nanowire chemistry.chemical_element Germanium 02 engineering and technology rapid thermal annealing 01 natural sciences 7. Clean energy Condensed Matter::Materials Science Aluminium 0103 physical sciences Thermal General Materials Science solid state exchanged reaction Nuclear Experiment 010302 applied physics business.industry Heterojunction Condensed Matter::Mesoscopic Systems and Quantum Hall Effect 021001 nanoscience & nanotechnology Atomic diffusion chemistry Quantum dot aluminum [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci] Optoelectronics 0210 nano-technology business |
| Zdroj: | ACS Applied Nano Materials ACS Applied Nano Materials, 2020, 3 (2), pp.1891-1899. ⟨10.1021/acsanm.9b02564⟩ |
| ISSN: | 2574-0970 |
| DOI: | 10.1021/acsanm.9b02564 |
| Popis: | International audience; The thermal activated solid state reaction forming aluminum–germanium nanowire (NW) heterostructures is a promising system as very sharp and well-defined one-dimensional contacts can be created between a metal and a semiconductor, that can become a quantum dot if the size becomes sufficiently small. In the search for high performance devices without variability, it is of high interest to allow deterministic fabrication of nanowire quantum dots, avoiding sample variability and obtaining atomic scale precision on the fabricated dot size. In this paper, we present a proof of principle experiment to produce sub-10 nm Ge quantum disks (QDs), using a combination of ex-situ thermal annealing via rapid thermal annealing (RTA) and in-situ Joule heating technique in a transmission electron microscope (TEM). First we present in-situ direct joule heating experiments showing how the heating electrode could be damaged due to the formation of Al crystals and voids at the vicinity of the metal/NW contact, likely related with electro-migration phenomena. We show that the contact quality can be preserved by including an additional ex-situ RTA step prior to the in-situ heating. The in-situ observations also show in real-time how the exchange reaction initiates simultaneously from several locations underneath the Al contact pad, and the Al crystal grows gradually inside the initial Ge NW with the growth interface along a Ge {111} lattice plane. Once the reaction front moves out from underneath the contact metal, two factors jeopardize an atomically accurate control of the Al/Ge reaction interface. We observed a local acceleration of the reaction interface due to the electron beam irradiation in the transmission electron microscope as well as the appearance of large jumps of the interface in unpassivated Ge wires, whereas a smooth advancement of the reaction interface was observed in wires with an Al$_2$O$_3$ passivation shell on the surface. Carefully controlling all aspects of the exchange reaction, we demonstrate a proof of principle experiment combining ex-situ and in-situ heating techniques to precisely control and produce axial Al/Ge/Al NW heterostructures with an ultrashort Ge segment down to 7 nm. Practically, the scaling down of the Ge segment length is only limited by the microscope resolution. |
| Databáze: | OpenAIRE |
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