All-wurtzite (In,Ga)As-(Ga,Mn)As core-shell nanowires grown by molecular beam epitaxy
Aloyzas Siusys, Janusz Sadowski, Maciej Sawicki, Slawomir Kret, Tomasz Wojciechowski, Katarzyna Gas, Wojciech Szuszkiewicz, Agnieszka Kaminska, Tomasz Story
Structural and magnetic properties of (In,Ga)As-(Ga,Mn)As core-shell nanowires grown by molecular beam epitaxy on GaAs(111)B substrate with gold catalyst have been investigated.(In,Ga)As core nanowires were grown at high temperature (500 °C) whereas (Ga,Mn)As shells were deposited on the {1-100} side facets of the cores at much lower temperature (220 °C). High resolution transmission electron microscopy images and high spectral resolution Raman scattering data show that both the cores and the shells of the nanowires have wurtzite crystalline structure. Scanning and transmission electron microscopy observations show smooth (Ga,Mn)As shells containing 5% of Mn epitaxially deposited on (In,Ga)As cores containing about 10% of In, without any misfit dislocations at the core-shell interface. With the In content in the (In,Ga)As cores larger than 5% the (In,Ga)As lattice parameter is higher than that of (Ga,Mn)As and the shell is in the tensile strain state. Elaborated magnetic studies indicate the presence of ferromagnetic coupling in (Ga,Mn)As shells at the temperatures in excess of 33 K. This coupling is maintained only in separated mesoscopic volumes resulting in an overall superparamagnetic behavior which gets blocked below ~17 K.
Phase-Controlled Epitaxy and Anisotropic Antiferromagnetism of Polar Wurtzite MnTe
Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所）；Centre of Excellence ENSEMBLE3 Sp. z o.o.（ENSEMBLE3卓越中心有限公司）；International Research Centre Magtop, Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所磁顶国际研究中心）；Center for Science and Innovation in Spintronics, Tohoku University（东北大学自旋电子学科学与创新中心）；Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University（东北大学电气通信研究所纳米电子与自旋电子学实验室）
Moire based strain analysis in wurtzite GaAs -- rock-salt (Pb,Sn)Te core-shell nanowires grown by molecular beam epitaxy
Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所）；Faculty of Physics, University of Warsaw（华沙大学物理学院）；Ensemble3 Centre of Excellence（Ensemble3卓越中心）；International Research Center MagTop, Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所国际研究中心MagTop）
The accurate control of the crystal phase in III-V semiconductor nanowires (NWs) is an important milestone for device applications. In this work, we present a method to select and maintain the wurtzite (WZ) crystal phase in self-assisted NWs. By choosing a specific regime where the NW growth process is a self-regulated system, the main experimental parameter to select the zinc-blende (ZB) or WZ phase is the V/III flux ratio. The latter can be monitored by changing the As flux, and drives the system toward a stationary regime when the wetting angle of the Ga droplet falls in a target interval, …
Incorporation of Bi into GaAs-(Ga,Al)As-Ga(As,Bi) core-shell nanowires grown by molecular beam epitaxy is studied with transmission electron microscopy. Nanowires are grown on GaAs(111)B substrates with Au-droplet assisted mode. Bi-doped shells are grown at low temperature (300 °C) with a close to stoichiometric Ga/As flux ratio. At low Bi fluxes, the Ga(As,Bi) shells are smooth, with Bi completely incorporated into the shells. Higher Bi fluxes (Bi/As flux ratio ~ 4%) led to partial segregation of Bi as droplets on the nanowires sidewalls, preferentially located at the nanowire segments with w…
Comprehensive investigation on the correlation of growth, structural and optical properties of GaN nanowires grown on Si(111) substrates by plasma assisted molecular beam epitaxy technique
Chiral Epitaxy: Enantioselective Growth of Chiral Nanowires on Low-Symmetry Two-Dimensional Materials
Weizmann Institute of Science（魏茨曼科学研究所）；Massachusetts Institute of Technology（麻省理工学院）；Université Paris-Saclay（巴黎萨克雷大学）；Federal University of ABC（ABC联邦大学）；State University of Campinas（坎皮纳斯州立大学）；De Shalit High School（德沙拉希特高中）；Tel Aviv University（特拉维夫大学）
Hexagonal group IV materials like silicon and germanium are expected to display remarkable optoelectronic properties for future development of photonic technologies. However, the fabrication of hexagonal group IV semiconductors within the vapour-liquid-solid method has been obtained using gold as a catalyst thus far. In this letter, we show the synthesis of hexagonal Ge on self-assisted GaAs nanowires using molecular beam epitaxy. With an accurate tuning of the Ga and As molecular beam flux we selected the crystal phase, cubic or hexagonal, of the GaAs NWs during the growth. A 500 nm-long hexa…
Hybrid semiconductor-superconductor InAs-Al nanowires with uniform and defect-free crystal interfaces are one of the most promising candidates used in the quest for Majorana zero modes (MZMs). However, InAs nanowires often exhibit a high density of randomly distributed twin defects and stacking faults, which result in an uncontrolled and non-uniform InAs-Al interface. Furthermore, this type of disorder can create potential inhomogeneity in the wire, destroy the topological gap, and form trivial sub-gap states mimicking MZM in transport experiments. Further study shows that reducing the InAs na…
We investigate the full and half-shells of Pb(1-x)Sn(x)Te topological crystalline insulator deposited by molecular beam epitaxy on the sidewalls of wurtzite GaAs nanowires (NWs). Due to the distinct orientation of the IV-VI shell with respect to the III-V core the lattice mismatch along the nanowire axis is less than 4%. The Pb(1-x)Sn(x)Te solid solution is chosen due to the topological crystalline insulator properties for some critical concentrations of Sn (x >= 0.4). The IV-VI shells are grown with different compositions spanning from binary SnTe, through Pb(1-x)Sn(x)Te with decreasing x val…
N-type doping of GaAs nanowires has proven to be difficult because the amphoteric character of silicon impurities is enhanced by the nanowire growth mechanism and growth conditions. The controllable growth of n-type GaAs nanowires with carrier density as high as 1020 electron/cm3 by self-assisted molecular beam epitaxy using Te donors is demonstrated here. Carrier density and electron mobility of highly doped nanowires are extracted through a combination of transport measurement and Kelvin probe force microscopy analysis in single-wire field-effect devices. Low-temperature photoluminescence is…
Indium antimonide (InSb) nanowires are used as building blocks for quantum devices because of their unique properties, i.e., strong spin-orbit interaction and large Landé g-factor. Integrating InSb nanowires with other materials could potentially unfold novel devices with distinctive functionality. A prominent example is the combination of InSb nanowires with superconductors for the emerging topological particles research. Here, we combine the II-VI cadmium telluride (CdTe) with the III-V InSb in the form of core-shell (InSb-CdTe) nanowires and explore potential applications based on the elect…
Self-selective growth of GaAs1-xBix on GaAs zinc blende/wurtzite nanowire heterostructures
Lund University（隆德大学）；NanoLund, Lund University（隆德大学纳米隆德）；Centre for Analysis and Synthesis, Lund University（隆德大学分析与合成中心）；MAX IV Laboratory, Lund University（隆德大学MAX IV实验室）；Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯玻尔研究所）
Topological quantum computing is based on braiding of Majorana zero modes encoding topological qubits. A promising candidate platform for Majorana zero modes is semiconductor-superconductor hybrid nanowires. The realization of topological qubits and braiding operations requires scalable and disorder-free nanowire networks. Selective area growth of in-plane InAs and InSb nanowires, together with shadow-wall growth of superconductor structures, have demonstrated this scalability by achieving various network structures. However, the noticeable lattice mismatch at the nanowire-substrate interface,…
Here we report on detailed studies of the magnetic properties of the wurtzite (Ga,Mn)As cylindrical shells. Ga$_{0.94}$Mn$_{0.06}$As shells have been grown by molecular beam epitaxy at low temperature as a part of multishell cylinders overgrown on wurtzite (Ga,In)As nanowires cores, synthesized on GaAs (111)B substrates. Our studies clearly indicate the presence of a low temperature ferromagnetic coupling, which despite a reasonably high Mn contents of 6\% is limited only to below 30~K. A set of dedicated measurements shows that despite a high structural quality of the material the magnetic or…
