Wafer-Scale Epitaxial Modulation of Quantum Dot Density
N. Bart, C. Dangel, P. Zajac, N. Spitzer, J. Ritzmann, M. Schmidt, H. G. Babin, R. Schott, S. R. Valentin, S. Scholz, Y. Wang, R. Uppu, D. Najer, M. C. Löbl, N.… 展开作者
N. Bart, C. Dangel, P. Zajac, N. Spitzer, J. Ritzmann, M. Schmidt, H. G. Babin, R. Schott, S. R. Valentin, S. Scholz, Y. Wang, R. Uppu, D. Najer, M. C. Löbl, N. Tomm, A. Javadi, N. O. Antoniadis, L. Midolo, K. Müller, R. J. Warburton, P. Lodahl, A. D. Wieck, J. J. Finley, A. Ludwig
Precise control of the properties of semiconductor quantum dots (QDs) is vital for creating novel devices for quantum photonics and advanced opto-electronics. Suitable low QD-density for single QD devices and experiments are challenging to control during epitaxy and are typically found only in limited regions of the wafer. Here, we demonstrate how conventional molecular beam epitaxy (MBE) can be used to modulate the density of optically active QDs in one- and two- dimensional patterns, while still retaining excellent quality. We find that material thickness gradients during layer-by-layer growth result in surface roughness modulations across the whole wafer. Growth on such templates strongly influences the QD nucleation probability. We obtain density modulations between 1 and 10 QDs/$μm^{2}$ and periods ranging from several millimeters down to at least a few hundred microns. This novel method is universal and expected to be applicable to a wide variety of different semiconductor material systems. We apply the method to enable growth of ultra-low noise QDs across an entire 3-inch semiconductor wafer.
We demonstrate single crystal growth of wafer-scale hexagonal boron nitride (hBN), an insulating atomic thin monolayer, on high-symmetry index surface plane Cu(111). The unidirectional epitaxial growth is guaranteed by large binding energy difference, ~0.23 eV, between A- and B-steps edges on Cu(111) docking with B6N7 clusters, confirmed by density functional theory calculations.
Epitaxial Al/GaAs/Al structures having controlled thickness of high-quality GaAs and pristine interfaces have been fabricated using a wafer-bonding technique. III-V semiconductor/Al structures are grown by molecular beam epitaxy on III-V semiconductor substrates and bonded to silicon and sapphire. Selective etching is used to remove the III-V substrate followed by surface cleaning and superconductor regrowth, resulting in epitaxial Al/GaAs/Al tri-layers on sapphire or silicon substrates. Structures are characterized with reflection high energy electron diffraction, atomic force microscopy, X-r…
An in vacuo thermal desorption process has been accomplished to form epitaxial graphene (EG) on 4H- and 6H-SiC substrates using a commercial chemical vapor deposition reactor. Correlation of growth conditions and the morphology and electrical properties of EG are described. Raman spectra of EG on Si-face samples were dominated by monolayer thickness. This approach was used to grow EG on 50 mm SiC wafers that were subsequently fabricated into field effect transistors with fmax of 14 GHz.
High-performance graphene field-effect transistors have been fabricated on epitaxial graphene synthesized on a two-inch SiC wafer, achieving a cutoff frequency of 100 GHz for a gate length of 240 nm. The high-frequency performance of these epitaxial graphene transistors not only shows the highest speed for any graphene devices up to date, but it also exceeds that of Si MOSFETs at the same gate length. The result confirms the high potential of graphene for advanced electronics applications, marking an important milestone for carbon electronics.
We demonstrate that the confocal laser scanning microscopy (CLSM) provides a non-destructive, highly-efficient characterization method for large-area epitaxial graphene and graphene nanostructures on SiC substrates, which can be applied in ambient air without sample preparation and is insusceptible to surface charging or surface contamination. Based on the variation of reflected intensity from regions covered by interfacial layer, single layer, bilayer, or few layer graphene, and through the correlation to the results from Raman spectroscopy and SPM, CLSM images with a high resolution (around …
Single layer hexagonal boron nitride is produced on 2 inch Pt(111)/sapphire wafers. The growth with borazine vapour deposition at process temperatures between 1000 and 1300 K is in-situ investigated by photoelectron yield measurements. The growth kinetics is slower at higher temperatures and follows a tanh$^2$ law which better fits for higher temperatures. The crystal-quality of h-BN/Pt(111) is inferred from scanning low energy electron diffraction (x-y LEED). The data indicate a strong dependence of the epitaxy on the growth temperature. The dominant structure is an aligned coincidence lattic…
Freestanding single-crystalline membranes are an important building block for functional electronics. Especially, compounds semiconductor membranes such as III-N and III-V offer great opportunities for optoelectronics, high-power electronics, and high-speed computing. Despite huge efforts to produce such membranes by detaching epitaxial layers from donor wafers, however, it is still challenging to harvest epitaxial layers using practical processes. Here, we demonstrate a method to grow and harvest multiple epitaxial membranes with extremely high throughput at the wafer scale. For this, 2D mate…
Two-dimensional (2D) materials have attracted substantial attention in electronic and optoelectronic applications with superior advantages of being flexible, transparent and highly tunable. Gapless graphene exhibits ultra-broadband and fast photoresponse while the 2D semiconducting MoS2 and GaTe unveil high sensitivity and tunable responsivity to visible light. However, the device yield and the repeatability call for a further improvement of the 2D materials to render large-scale uniformity. Here we report a layer-by-layer growth of wafer-scale GaTe with a hole mobility of 28.4 cm2/Vs by molec…
The development of graphene electronics requires the integration of graphene devices with Si-CMOS technology. Most strategies involve the transfer of graphene sheets onto silicon, with the inherent difficulties of clean transfer and subsequent graphene nano-patterning that degrades considerably the electronic mobility of nanopatterned graphene. Epitaxial graphene (EG) by contrast is grown on an essentially perfect crystalline (semi-insulating) surface, and graphene nanostructures with exceptional properties have been realized by a selective growth process on tailored SiC surface that requires …
Two-dimensional (2D) indium monoselenide (InSe) has attracted significant attention as a III-VI two-dimensional semiconductor (2D) with a combination of favorable attributes from III-V semiconductors as well as van der Waals 2D transition metal dichalcogenides. Nevertheless, the large-area synthesis of phase-pure 2D InSe remains unattained due to the complexity of the binary In-Se system and the difficulties in promoting lateral growth. Here, we report the first polymorph-selective synthesis of epitaxial 2D InSe by metal-organic chemical deposition (MOCVD) over 2 inch diameter sapphire wafers.…
The formation of graphene on any desirable substrate is extremely essential for the successful replacement of Si with graphene in all technological applications in the beyond-CMOS era. Recently, we observed that a Ti layer formed on epitaxial graphene by electron-beam evaporation has the sufficiently large area of contact with the surface of epitaxial graphene for the exfoliation process to take place. We also observed that the exfoliated FLG on the Ti layer can be easily transferred onto a SiO2/Si substrate. In this paper, we have proposed a new technique for transferring graphene having a la…
Up to two layers of epitaxial graphene have been grown on the Si-face of two-inch SiC wafers exhibiting room-temperature Hall mobilities up to 1800 cm^2/Vs, measured from ungated, large, 160 micron x 200 micron Hall bars, and up to 4000 cm^2/Vs, from top-gated, small, 1 micron x 1.5 micron Hall bars. The growth process involved a combination of a cleaning step of the SiC in a Si-containing gas, followed by an annealing step in Argon for epitaxial graphene formation. The structure and morphology of this graphene has been characterized using AFM, HRTEM, and Raman spectroscopy. Furthermore, top-g…
We report a direct correlation between carrier mobility and Raman topography of epitaxial graphene (EG) grown on silicon carbide (SiC). We show the Hall mobility of material on the Si-face of SiC [SiC(0001)] is not only highly dependent on thickness uniformity but also on monolayer strain uniformity. Only when both thickness and strain are uniform over a significant fraction (> 40%) of the device active area does the mobility exceed 1000 cm2/V-s. Additionally, we achieve high mobility epitaxial graphene (18,100 cm2/V-s at room temperature) on the C-face of SiC [SiC(000-1)] and show that carrie…
Realization of wafer-scale single-crystal films of transition metal dichalcogenides (TMDs) such as tungsten sulfide requires epitaxial growth and coalescence of oriented domains to form a continuous monolayer. The domains must be oriented in the same crystallographic direction on the substrate to avoid the formation of metallic inversion domain boundaries (IDBs) which are a common feature of layered chalcogenides. Here we demonstrate fully-coalesced single orientation tungsten sulfide monolayers on 2-inch diameter c-plane sapphire by metalorganic chemical vapor deposition using a multi-step gr…
Epitaxial growth and controllable doping of wafer-scale single-crystal transition-metal dichalcogenides (TMDCs) are two central tasks for extending Moore's law beyond silicon. However, despite considerable efforts, addressing such crucial issues simultaneously under two-dimensional (2D) confinement is yet to be realized. Here we design an ingenious epitaxial strategy to synthesize record-breaking 4-inch single-crystal Fe-doped TMDCs monolayers on industry-compatible c-plane sapphire without miscut angle. In-depth characterizations and theoretical calculations reveal that the introduction of Fe…
The Diels-Alder surface modified top epitaxial graphene layer, with newly created pair of sp3 carbon centres, results in abrupt minimization of interlayer van der Waals interactions between two stacked graphene planes, and escapes the wafer during post-reaction manipulation stage, leaving the layer under it almost pristine-like. Above picture shows Diels-Alder functionalized sp2/sp3 graphene adduct leaves the parent wafer. In this communication we systematically address several fundamental questions in graphene surface chemistry, which are of extreme importance for device fabrication, and in s…
Homogeneous highly epitaxial LaSrMnO3 (LSMO) thin films have been grown on Yttria-stabilized-Zirconia (YsZ) / CeO2 buffer layers on technological relevant 4" silicon wafers using a Twente Solid State Technology B.V. (TSST) developed large area Pulsed Laser Deposition (PLD) setup. We study and show the results of the effect of an additional SrRuO3 buffer layer on the growth temperature dependent structural and magnetic properties of LSMO films. With the introduction of a thin SrRuO3 layer on top of the buffer stack, LSMO films show ferromagnetic behaviour for growth temperatures as low as 250C.…
The epitaxial growth of two-dimensional (2D) $β-In_2Se_3$ material was obtained over 2-inches c-sapphire wafers using molecular beam epitaxy (MBE). Excellent quality of thick (90 nm) and very thin films, down to two quintuple layers (2 nm), was confirmed by x-ray diffraction (XRD), Raman spectroscopy, and aberration-corrected scanning transmission electron microscopy (ac-STEM). Wafer-scale fabrication of photodetectors based on five quintuple layers was produced using photolithography and other standard semiconductor processing methods. The photodetectors exhibit responsivity of 3 mA/W, peak s…
Ultraviolet-C light-emitting diodes (UVC-LEDs) have great application in pathogen inactivation under various kinds of situations, especially in the fight against the COVID-19. Unfortunately, its epitaxial wafers are so far limited to 2-inch size, which greatly increases the cost of massive production. In this work, we report the 4-inch crack-free high-power UVC-LED wafer. This achievement relies on a proposed strain-tailored strategy, where a three-dimensional to two-dimensional (3D-2D) transition layer is introduced during the homo-epitaxy of AlN on high temperature annealed (HTA)-AlN templat…
Transition metal dichalcogenide (TMD) monolayers and heterostructures have emerged as a compelling class of materials with transformative new science that may be harnessed for novel device technologies. These materials are commonly fabricated by exfoliation of flakes from bulk crystals, but wafer-scale epitaxy of single crystal films is required to advance the field. This article reviews the fundamental aspects of epitaxial growth of van der Waals bonded crystals specific to TMD films. The structural and electronic properties of TMD crystals are initially described along with sources and metho…
Transition metal dichalcogenides (TMDs) are materials that can exhibit intriguing optical properties like a change of the bandgap from indirect to direct when being thinned down to a monolayer. Well-resolved narrow excitonic resonances can be observed for such monolayers, however only for materials of sufficient crystalline quality, so far mostly available in the form of micrometer-sized flakes. A further significant improvement of optical and electrical properties can be achieved by transferring the TMD on hexagonal boron nitride (hBN). To exploit the full potential of TMDs in future applicat…
We present a new fabrication method for epitaxial graphene on SiC which enables the growth of ultra-smooth defect- and bilayer-free graphene sheets with an unprecedented reproducibility, a necessary prerequisite for wafer-scale fabrication of high quality graphene-based electronic devices. The inherent but unfavorable formation of high SiC surface terrace steps during high temperature sublimation growth is suppressed by rapid formation of the graphene buffer layer which stabilizes the SiC surface. The enhanced nucleation is enforced by decomposition of polymer adsorbates which act as a carbon …
Growth of epitaxial graphene on the C-face of SiC has been investigated. Using a confinement controlled sublimation (CCS) method, we have achieved well controlled growth and been able to observe propagation of uniform monolayer graphene. Surface patterns uncover two important aspects of the growth, i.e. carbon diffusion and stoichiometric requirement. Moreover, a new "stepdown" growth mode has been discovered. Via this mode, monolayer graphene domains can have an area of hundreds of square micrometers, while, most importantly, step bunching is avoided and the initial uniformly stepped SiC surf…
Wafer-scale Demonstration of High-voltage beta-Ga2O3 MOSFETs with Excellent Uniformity and over 3kV Breakdown Voltages
Yongjiang Laboratory（甬江实验室）；Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences（中国科学院宁波材料技术与工程研究所）；School of Microelectronics, Fudan University（复旦大学微电子学院）；Hangzhou Garen Semiconductor Co., Ltd.（杭州嘉然半导体有限公司）
Radiative efficiency of highly luminescent bulk InP wafers severely degrades upon heat treatment involved in epitaxial growth of quaternary layers and fabrication of photodiodes on the surface. This unfortunate property impedes the use of bulk InP as scintillator material. On the other hand, it is known that thin epitaxial InP layers, grown by molecular beam epitaxy (MBE) or metal-organic chemical vapor deposition (MOCVD), do not exhibit any degradation. These layers, however, are too thin to be useful in scintillators. The capability of hydride vapor phase epitaxy (HVPE) process to grow thick…
We have investigated epitaxial graphene films grown on SiC(0001) by annealing in an atmosphere of Ar instead of vacuum. Using AFM and LEEM we observe a significantly improved surface morphology and graphene domain size. Hall measurements on monolayer graphene films show a carrier mobility of around 1000 cm^2/Vs at room temperature and 2000 cm^2/Vs at 27K. The growth process introduced here establishes the synthesis of graphene films on a technologically viable basis.
The materials science of graphene grown epitaxially on the hexagonal basal planes of SiC crystals is reviewed. We show that the growth of epitaxial graphene on Si-terminated SiC(0001) is much different than growth on the C-terminated SiC(000 -1) surface, and discuss the physical structure of these graphenes. The unique electronic structure and transport properties of each type of epitaxial graphene is described, as well as progress toward the development of epitaxial graphene devices. This materials system is rich in subtleties, and graphene grown on the two polar faces differs in important wa…
Growth of two-dimensional van der Waals layered single-crystal (SC) films is highly desired to manifest intrinsic material sciences and unprecedented devices for industrial applications. While wafer-scale SC hexagonal boron nitride film has been successfully grown, an ideal growth platform for diatomic transition metal dichalcogenide (TMdC) film has not been established to date. Here, we report the SC growth of TMdC monolayers in a centimeter scale via atomic sawtooth gold surface as a universal growth template. Atomic tooth-gullet surface is constructed by the one-step solidification of liqui…
Ulta-wide bandgap semiconductors based on $β$-Ga$_2$O$_3$ offer the potential to achieve higher power switching performance, efficiency, and lower manufacturing cost than today's wide bandgap power semiconductors. However, the most critical challenge to the commercialization of Ga$_2$O$_3$ electronics is overheating, which impacts the device's performance and reliability. We fabricated a Ga$_2$O$_3$/4H-SiC composite wafer using a fusion-bonding method. A low temperature ($\le$ 600 $^{\circ}$C) epitaxy and device processing approach based on low-temperature (LT) metalorganic vapor phase epitaxy…
We investigated the Dirac-cone state and its modulation when an ultrathin film of topological insulator Bi2Se3 was epitaxially grown on a van-der-Waals ferromagnet Cr2Si2Te6 (CST) by angle-resolved photoemission spectroscopy. We observed a gapless Dirac-cone surface state in 6 quintuple-layer (QL) Bi2Se3 on CST, whereas the Dirac cone exhibits a gap of 0.37 eV in 2QL counterpart. Intriguingly, this gap is much larger than those for Bi2Se3 films on Si(111). We also revealed no discernible change in the gap magnitude across the ferromagnetic transition of CST, suggesting the very small character…
Germanium (Ge) is increasingly used as a substrate for high-performance optoelectronic, photovoltaic, and electronic devices. These devices are usually grown on thick and rigid Ge substrates manufactured by classical wafering techniques. Nanomembranes (NMs) provide an alternative to this approach while offering wafer-scale lateral dimensions, weight reduction, limitation of waste, and cost effectiveness. Herein, we introduce the Porous germanium Efficient Epitaxial LayEr Release (PEELER) process, which consists of the fabrication of wafer-scale detachable monocrystalline Ge NMs on porous Ge (P…
Temperature dependent magnetometry and transport measurements on epitaxial Fe3O4 films grown on BaTiO3(100) single crystals by molecular beam epitaxy show a series of discontinuities, that are due to changes in the magnetic anisotropy induced by strain in the different crystal phases of BaTiO3. The magnetite film is under tensile strain at room temperature, which is ascribed to the lattice expansion of BaTiO3 at the cubic to tetragonal transition, indicating that the magnetite film is relaxed at the growth temperature. From the magnetization versus temperature curves, the variation in the magn…
Graphene is a powerful playground for studying a plethora of quantum phenomena. One of the remarkable properties of graphene arises when it is strained in particular geometries and the electrons behave as if they were under the influence of a magnetic field. Previously, these strain-induced pseudomagnetic fields have been explored on the nano- and micrometer-scale using scanning probe and transport measurements. Heteroepitaxial strain, in contrast, is a wafer-scale engineering method. Here, we show that pseudomagnetic fields can be generated in graphene through wafer-scale epitaxial growth. Sh…
We use ultra-high vacuum chemical vapor deposition to grow polycrystalline silicon carbide (SiC) on c-plane sapphire wafers which are then annealed between 1250 and 1450°C in vacuum to create epitaxial multilayer graphene (MLG). Despite the surface roughness and small domain size of the polycrystalline SiC, a conformal MLG film is formed. By planarizing the SiC prior to graphene growth, a reduction of the Raman defect band is observed in the final MLG. The graphene formed on polished SiC films also demonstrates significantly more ordered layer-by-layer growth and increased carrier mobility for…
High thermal conductivity electronic materials are critical components for high-performance electronic and photonic devices as either active functional materials or thermal management materials. We report an isotropic high thermal conductivity over 500 W m-1K-1 at room temperature in high-quality wafer-scale cubic silicon carbide (3C-SiC) crystals, which is the second highest among large crystals (only surpassed by diamond). Furthermore, the corresponding 3C-SiC thin films are found to have record-high in-plane and cross-plane thermal conductivity, even higher than diamond thin films with equi…
We present a technique to tune the charge density of epitaxial graphene via an electrostatic gate that is buried in the silicon carbide substrate. The result is a device in which graphene remains accessible for further manipulation or investigation. Via nitrogen or phosphor implantation into a silicon carbide wafer and subsequent graphene growth, devices can routinely be fabricated using standard semiconductor technology. We have optimized samples for room temperature as well as for cryogenic temperature operation. Depending on implantation dose and temperature we operate in two gating regimes…
Pentacene has been used widely in organic devices, and the interface structure between pentacene and a substrate is known to significantly influence device performances. Here we demonstrate that molecular ordering of pentacene on graphene depends on the interaction between graphene and its underlying SiC substrate. The adsorption of pentacene molecules on zero-layer and single-layer graphene, which were grown on a Sifaced 6H-SiC(0001) wafer, was studied using scanning tunneling microscopy (STM). Pentacene molecules form a quasi-amorphous layer on zero-layer graphene which interacts strongly wi…
It is crucial for the studies of the transport properties and quantum effects related to Dirac surface states of three-dimensional topological insulators (3D TIs) to be able to simultaneously tune the chemical potentials of both top and bottom surfaces of a 3D TI thin film. We have realized this in molecular beam epitaxy-grown thin films of 3D TIs, as well as magnetic 3D TIs, by fabricating dual-gate structures on them. The films could be tuned between n-type and p-type by each gate alone. Combined application of two gates can reduce the carrier density of a TI film to a much lower level than …
Intercalation of atomic species through epitaxial graphene layers began only a few years following its initial report in 2004. The impact of intercalation on the electronic properties of the graphene is well known; however, the intercalant itself can also exhibit intriguing properties not found in nature. This suggests that a shift in the focus of epitaxial graphene intercalation studies may lead to fruitful exploration of many new forms of traditionally 3D materials. In the following forward-looking review, we summarize the primary techniques used to achieve and characterize EG intercalation,…
Operation of semiconductor scintillators requires optically-tight integration of the photoreceiver system on the surface of the scintillator slab. We have implemented an efficient and fast quaternary InGaAsP pin photodiode, epitaxially grown upon the surface of an InP scintillator wafer and sensitive to InP luminescence. The diode is characterized by an extremely low room-temperature dark current, about 1 nA/cm2 at the reverse bias of 2 V. The low leakage makes possible a sensitive readout circuitry even though the diode has a large area (1 mm/times1 mm) and therefore large capacitance (50 pF)…
Atomically thin MoS2/graphene heterostructures are promising candidates for nanoelectronic and optoelectronic technologies. Among different graphene substrates, epitaxial graphene (EG) on SiC provides several potential advantages for such heterostructures including high electronic quality, tunable substrate coupling, wafer-scale processability, and crystalline ordering that can template commensurate growth. Exploiting these attributes, we demonstrate here the thickness-controlled van der Waals epitaxial growth of MoS2 on EG via chemical vapor deposition, giving rise to transfer-free synthesis …
Ge/SiGe multi-quantum well heterostructures are highly sought-after for silicon-integrated optoelectronic devices operating in the broad range of the electromagnetic spectrum covering infrared to terahertz wavelengths. However, the epitaxial growth of these heterostructures at a thickness of a few microns has been a challenging task due the lattice mismatch and its associated instabilities resulting from the formation of growth defects. To elucidates these limits, we outline herein a process for the strain-balanced growth on silicon of 11.1 nm/21.5 nm Ge/Si0.18Ge0.82 superlattices (SLs) with a…
We report the use of a surfactant molecule during the epitaxy of graphene on SiC(0001) that leads to the growth in an unconventional orientation, namely $R0^\circ$ rotation with respect to the SiC lattice. It yields a very high-quality single-layer graphene with a uniform orientation with respect to the substrate, on the wafer scale. We find an increased quality and homogeneity compared to the approach based on the use of a pre-oriented template to induce the unconventional orientation. Using spot profile analysis low energy electron diffraction, angle-resolved photoelectron spectroscopy, and …
Nanoporous materials represent a versatile solution for a number of applications ranging from sensing, energy applications, catalysis, drug delivery, and many others. The synergy between the outstanding properties of graphene with a three-dimensional porous structure, circumventing the limits of its 2D nature, constitutes therefore a breakthrough for many fields. We report the first three-dimensional growth of epitaxial graphene on a porousified crystalline 4H-SiC(0001). The wafer porosification is performed via a sequence of metal-assisted photochemical and photoelectrochemical etching in hyd…
We present a study of the lattice response to the compressive and tensile biaxial stress in La0.67Sr0.33MnO3 (LSMO) and SrRuO3 (SRO) thin films grown on a variety of single crystal substrates: SrTiO3, DyScO3, NdGaO3 and (La,Sr)(Al,Ta)O3. The results show, that in thin films under misfit strain, both SRO and LSMO lattices, which in bulk form have orthorhombic (SRO) and rhombohedral (LSMO) structures, assume unit cells that are monoclinic under compressive stress and tetragonal under tensile stress. The applied stress effectively modifies the BO6 octahedra rotations, which degree and direction c…
The rapid discovery of two-dimensional (2D) van der Waals (vdW) quantum materials has led to heterostructures that integrate diverse quantum functionalities such as topological phases, magnetism, and superconductivity. In this context, the epitaxial synthesis of vdW heterostructures with well-controlled interfaces is an attractive route towards wafer-scale platforms for systematically exploring fundamental properties and fashioning proof-of-concept devices. Here, we use molecular beam epitaxy to synthesize a vdW heterostructure that interfaces two material systems of contemporary interest: a 2…
Here, we demonstrate an approach that provides a precise control of the dimension of InAs from one-dimensional nanowires to wafer-scale free-standing two-dimensional nanosheets, which have a high degree of crystallinity and outstanding electrical and optical properties, using molecular-beam epitaxy by controlling catalyst alloy segregation. In our approach, two-dimensional InAs nanosheets can be obtained directly from one-dimensional InAs nanowires by silver-indium alloy segregation, which is much easier than all previously reported method, such as traditional buffering technique and select ar…
Graphene and related materials can lead to disruptive advances in next generation photonics and optoelectronics. The challenge is to devise growth, transfer and fabrication protocols providing high (>5,000 cm2 V-1 s-1) mobility devices with reliable performance at the wafer scale. Here, we present a flow for the integration of graphene in photonics circuits. This relies on chemical vapour deposition (CVD) of single layer graphene (SLG) matrices comprising up to ~12000 individual single crystals (SCs), grown to match the geometrical configuration of the devices in the photonic circuit. This is …
