A5101759066- Semiconductor Quantum Structures and Devices
- Quantum and electron transport phenomena
- Advancements in Semiconductor Devices and Circuit Design
- Semiconductor materials and interfaces
- Photonic and Optical Devices
- Photonic Crystals and Applications
- Nanowire Synthesis and Applications
- Semiconductor materials and devices
- Silicon Nanostructures and Photoluminescence
- Integrated Circuits and Semiconductor Failure Analysis
- Polymer crystallization and properties
- Semiconductor Lasers and Optical Devices
- Force Microscopy Techniques and Applications
- Physics of Superconductivity and Magnetism
- Ion-surface interactions and analysis
- Advanced Electron Microscopy Techniques and Applications
- Microplastics and Plastic Pollution
- Thin-Film Transistor Technologies
- Nonlinear Optical Materials Studies
- Quantum-Dot Cellular Automata
- Electronic and Structural Properties of Oxides
- Polymer Nanocomposites and Properties
- biodegradable polymer synthesis and properties
- Recycling and Waste Management Techniques
Johannes Kepler University of Linz
2016-2024
Institute of Science and Technology Austria
2018-2021
Holes confined in quantum dots have gained considerable interest the past few years due to their potential as spin qubits. Here we demonstrate two-axis control of a 3/2 qubit natural Ge. The is formed hut wire double dot device. Pauli blockade principle allowed us electric dipole resonance by applying radio frequency field one electrodes defining dot. Coherent hole oscillations with Rabi frequencies reaching 140 MHz are demonstrated and dephasing times 130 ns measured. reported results...
Hole spins have gained considerable interest in the past few years due to their potential for fast electrically controlled qubits. Here, we study holes confined Ge hut wires, a so-far unexplored type of nanostructure. Low-temperature magnetotransport measurements reveal large anisotropy between in-plane and out-of-plane g-factors up 18. Numerical simulations verify that this originates from wave function heavy-hole character. A light-hole admixture less than 1% is estimated states lowest...
Abstract Semiconductor nanowires have been playing a crucial role in the development of nanoscale devices for realization spin qubits, Majorana fermions, single photon emitters, nanoprocessors, etc. The monolithic growth site‐controlled is prerequisite toward next generation that will require addressability and scalability. Here, combining top‐down nanofabrication bottom‐up self‐assembly, Ge wires on prepatterned Si (001) substrates with controllable position, distance, length, structure...
The strong atomistic spin–orbit coupling of holes makes single-shot spin readout measurements difficult because it reduces the lifetimes. By integrating charge sensor into a high bandwidth radio frequency reflectometry setup, we were able to demonstrate germanium quantum dot hole and measure lifetime. Hole relaxation times about 90 μs at 500 mT are reported, with total visibility 70%. analyzing separately spin-to-charge conversion fidelities, have obtained insight processes limiting...
Abstract Reconfigurable field‐effect transistors, capable of being dynamically programmed during run‐time, overcome the static nature conventional complementary metal‐oxide semiconductors by reducing transistor count and circuit path delay. Thereby, SiGe Ge are predicted to boost drive currents, switching speed reduce power consumption. Nevertheless, Ge‐based reconfigurable prototypes have so far fallen short in reaching both promised performance due interface instability their contacts gate...
Abstract In situ transmission electron microscopy (TEM) is a powerful tool for advanced material characterization. It allows real-time observation of structural evolution at the atomic level while applying different stimuli such as heat. However, validity analysis strongly depends on quality specimen, which has to be prepared by thinning bulk transparency maintaining pristine properties. To address this challenge, novel method TEM samples preparation in plan-view geometry was elaborated...
Si1-x Gex is a key material in modern complementary metal-oxide-semiconductor and bipolar devices. However, despite considerable efforts metal-silicide -germanide compound systems, reliability concerns have so far hindered the implementation of metal-Si1-x junctions that are vital for diverse emerging "More than Moore" quantum computing paradigms. In this respect, systematic structural electronic properties Al-Si1-x heterostructures, obtained from thermally induced exchange between...
We report the resonantly enhanced radiative emission from a single SiGe quantum dot (QD), which is deterministically embedded into bichromatic photonic crystal resonator (PhCR) at position of its largest modal electric field by scalable method. By optimizing our molecular beam epitaxy (MBE) growth technique, we were able to reduce amount Ge within whole obtain an absolute minimum exactly one QD, accurately positioned lithographic methods relative PhCR, and otherwise flat, few monolayer thin,...
Using inelastic cotunneling spectroscopy we observe a zero field splitting within the spin triplet manifold of Ge hut wire quantum dots. The states with ±1 in confinement direction are energetically favored by up to 55 μeV compared 0 state because strong spin–orbit coupling. reported effect should be observable broad class strongly confined hole quantum-dot systems and might need considered when operating qubits.
The realization of several future electronic and optoelectronic Si‐based devices is impeded by the limited critical thickness strained, pseudomorphic, Ge‐rich Si 1− x Ge layers grown on Si(001) substrates, i.e., before their relaxation. Herein, atomic force microscopy used to investigate surface morphology about 170 /Si(001) samples with various compositions ranging from ≈36% 100% film thicknesses ≈1 ≈16 nm. Furthermore, defining quality standards concerning roughness, relaxation behavior...
Heavy holes confined in quantum dots are predicted to be promising candidates for the realization of spin qubits with long coherence times. Here we focus on such heavy-hole states Germanium hut wires. By tuning growth density latter can realize a T-like structure between two neighboring Such allows charge sensor, which is electrostatically and tunnel coupled dot, charge-transfer signals as high 0.3e. integrating into radio-frequency reflectometry setup, single-shot measurements allowing...
The Si/SiGe heterosystem would be ideally suited for the realization of complementary metal-oxide-semiconductor (CMOS)-compatible integrated light sources, but indirect band gap, exacerbated by a type-II offset, makes it challenging to achieve efficient emission. We address this problem strain engineering in ordered arrays vertically close-stacked SiGe quantum dot (QD) pairs. induced respective lower QD creates preferential nucleation site upper one and strains as well Si cap above it....
The lack of straightforward epitaxial integration useful telecom lasers on silicon remains the major bottleneck for bringing optical interconnect technology down to on-chip level. Crystalline itself, an indirect semiconductor, is a poor light emitter. Here, we identify conceptionally simple Si/Si$_{1-x}$Ge$_x$/Si double heterostructures (DHS) with large Ge content ($x \gtrsim 0.4$) as auspicious gain material suitable Si-based integrated optics. In particular, using self-consistent...
The realization of scalable telecom light emitters that can be monolithically implemented into large-scale Si integration technology has been a driving factor in the field photonics for last decades. Applications are envisioned short and medium-range data transfer realizing scalable, Si-based quantum information technology. For latter, CMOS-compatible sources controlled on single photon level needed. In solid-state materials, group-III-V dots (QDs) one leading platforms excellent optical...
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We investigate the nanoheteroepitaxy (NHE) of SiGe and Ge quantum dots (QDs) grown on nanotips (NTs) substrates realized in Si(001) wafers. Due to lattice strain compliance, enabled by nanometric size tip limited dot/substrate interface area, which helps reduce interdiffusion, composition QDs could be decoupled. This demonstrates a key advantage NHE over Stranski-Krastanow growth mechanism. Nearly semi-spherical, defect-free, ∼100 nm wide with different contents were successfully NTs high...
Quantum devices based on holes confined in crystalline Ge nanostructures have emerged as a promising platform the field of quantum technology. Epitaxial hutwires (HWs) successfully used pioneering bit (qubit) experiments are logical next choice for long‐distance coherent spin–spin coupling experiments. However, leakage currents currently limiting device performance HWs bulk Si substrates. This drawback can be mitigated by HW growth silicon‐on‐insulator (SOI) Herein, molecular beam epitaxy...
We firstly introduce the self-assembled growth of highly uniform Ge quantum wires with controllable position, distance and length on patterned Si (001) substrates. then present electrically tunable strong spin-orbit coupling, first hole spin qubit ultrafast operation in Ge/Si wires.
We report the resonantly enhanced radiative emission from a single SiGe quantum dot (QD), which is deterministically embedded into bichromatic photonic crystal resonator (PhCR) at position of its largest modal electric field by scalable method. By optimizing our molecular beam epitaxy (MBE) growth technique, we were able to reduce amount Ge within whole obtain an absolute minimum exactly one QD, accurately positioned lithographic methods relative PhCR, and otherwise flat, few monolayer thin,...
We report the resonantly enhanced radiative emission from a single SiGe quantum dot (QD), which is deterministically embedded into bichromatic photonic crystal resonator (PhCR) at position of its largest modal electric field by scalable method. By optimizing our molecular beam epitaxy (MBE) growth technique, we were able to reduce amount Ge within whole obtain an absolute minimum exactly one QD, accurately positioned lithographic methods relative PhCR, and otherwise flat, few monolayer thin,...