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Seminar: Thursday, 16th November 2023 at 3:30 pm

Alois Lugstein (TU Wien)

Title: Metal-Semiconductor-Metal Heterostructures for Electrical, Optical and Plasmonic Applications


Institut Néel, Room K223 (Rémy Lemaire)
Abstract: I will address the controlled formation of monolithic metal–semiconductor nanowire and nanosheet heterostructures. The main obstacles facing towards reliable synthesis of such hybrid systems are related to lateral strain relaxation, mitigating the limitations of material lattice compatibility and allow arbitrarily combined dissimilar materials unattainable in layered structures. Out of the wide range of nanowires, Ge combines a high carrier mobility, with a more than five times larger exciton Bohr radius compared to Si. Hence, Ge is of particular interest especially for the development of high speed and novel quantum devices.
The formation of axial and radial nanowire heterostructures with atomically sharp interfaces and monocrystalline aluminum leads by using a thermally initiated exchange reaction will be presented. This enables the fabrication of an in line contacted quantum dot without requiring precise lithographic alignment of the contacts, which is one of the most challenging issues of fabricating quantum dot based devices. Unambiguous signatures of quantum ballistic transport and electrostatically tunable negative differential resistance even at room temperature will be demonstrated and attributed to intervalley electron transfer.
Together with the wafer-scale accessibility, the proposed fabrication scheme may give rise to the development of key components for a broad spectrum of emerging Si and Ge-based devices requiring monolithic metal-semiconductor−metal heterostructures with high-quality interfaces for electrical, optical and plasmonic applications.