A5073818862- Semiconductor Quantum Structures and Devices
- Nanowire Synthesis and Applications
- Advancements in Semiconductor Devices and Circuit Design
- ZnO doping and properties
- Magnetic properties of thin films
- Photonic and Optical Devices
- Electronic and Structural Properties of Oxides
- Semiconductor Lasers and Optical Devices
- Semiconductor materials and devices
- Quantum and electron transport phenomena
- Semiconductor materials and interfaces
- Advanced Semiconductor Detectors and Materials
- Quantum Dots Synthesis And Properties
- Ga2O3 and related materials
- Heusler alloys: electronic and magnetic properties
- Surface and Thin Film Phenomena
- Magnetic and transport properties of perovskites and related materials
- Silicon Nanostructures and Photoluminescence
- Carbon and Quantum Dots Applications
- Advanced Photocatalysis Techniques
- Paleontology and Stratigraphy of Fossils
- Iron Metabolism and Disorders
- Topological Materials and Phenomena
- Physics of Superconductivity and Magnetism
- Nutritional Studies and Diet
University College London
2018-2024
Changchun Institute of Optics, Fine Mechanics and Physics
2024
Chinese Academy of Sciences
2012-2024
University of Chinese Academy of Sciences
2024
Institute of Semiconductors
2011-2023
Fujian Medical University
2023
Here we report the growth of phase-pure InAs nanowires on Si (111) substrates by molecular-beam epitaxy using Ag catalysts. A conventional one-step catalyst annealing process is found to give rise with diameters ranging from 4.5 81 nm due varying sizes droplets, which reveal strong diameter dependence crystal structure. In contrast, a novel two-step procedure yields vertical highly uniform ∼10 in diameter. Significantly, these ultrathin exhibit perfect wurtzite structure, free stacking...
Self-catalyzed growth of GaAs nanowires are widely ascribed to the vapor–liquid–solid (VLS) mechanism due presence Ga particles at nanowire tips. Here we report synthesis self-catalyzed by molecular-beam epitaxy covering a large parameter space. By carefully controlling flux and its ratio with As flux, without exhibiting flat front produced. Using scanning electron microscopy high-resolution transmission microscopy, compare rate structure, especially near front, droplets. We find that...
Growth of high-quality single-crystalline InSb layers remains challenging in material science. Such layered materials are highly desired for searching and manipulation Majorana Fermions solid state, a fundamental research task physics today, development novel high-speed nanoelectronic infrared optoelectronic devices. Here, we report on new route toward growth single-crystalline, materials. We demonstrate the successful free-standing, two-dimensional nanosheets one-dimensional InAs nanowires...
Combining self-catalyzed vapor-liquid-solid growth of GaAs nanowires and low-temperature molecular-beam epitaxy (Ga,Mn)As, we successfully synthesized all zinc-blende (ZB) GaAs/(Ga,Mn)As core-shell on Si(111) substrates. The ZB nanowire cores are first fabricated at high temperature by utilizing the Ga droplets as catalyst controlling triple phase line nucleation, then (Ga,Mn)As shells epitaxially grown side facets core low temperature. window for pure is found to be very narrow. Both...
Abstract Over the past decades, progress in growth of materials which can be applied to cutting-edge technologies field electronics, optoelectronics and energy harvesting has been remarkable. Among various materials, group III–V semiconductors are particular interest have widely investigated due their excellent optical properties high carrier mobility. However, integration structures as light sources numerous other components on Si, is foundation for most optoelectronic electronic integrated...
Abstract Monolithic integration of III–V materials and devices on CMOS compatible on‐axis Si (001) substrates enables a route low‐cost high‐density Si‐based photonic integrated circuits. Inversion boundaries (IBs) are defects that arise from the interface between Si, which makes it almost impossible to produce high‐quality Si. In this paper, novel technique achieve IB‐free GaAs monolithically grown by realizing alternating straight meandering single atomic steps surface has been demonstrated...
Uniform quantum dots (QDs) with a narrowed linewidth of photoluminescence (PL) are crucial for developing high-performance QD lasers. This study focuses on optimizing the growth conditions InAs QDs (001) InP substrates using metal-organic chemical vapor deposition (MOCVD), targeting applications in 1.55 µm By fine-tuning parameters such as V/III ratio, thickness, and temperature, we attained density 4.13 × 10 cm −2 . Further, PL full width at half maximum (FWHM) 40.1 meV was achieved...
Surface adsorption of organic molecules provides a new method for the robust manipulation ferromagnetism in (Ga,Mn)As. Electron acceptor and donor yield significant enhancement suppression, respectively, with modulation Curie temperature spanning 36 K. Dip-pen nanolithography is employed to directly pattern monolayers on (Ga,Mn)As, which presented as novel pathway toward producing magnetic nanostructures.
Epitaxial growth of III-V materials on a CMOS-compatible Si (001) substrate enables the feasibility mass production low-cost and high-yield Si-based optoelectronic devices. However, material dissimilarities between group-IV induce several types defects, especially threading dislocations (TDs) antiphase boundaries (APBs). The presence these defects is detrimental to device performance thus needs be eliminated. In this paper, mechanism APB annihilation during GaAs on-axis clarified, along with...
For the epitaxial growth of Ga-based III-V semiconductor nanowires (NWs) on Si, Ga droplets could provide a clean and compatible solution in contrast to common Au catalyst. However, use is rather limited except for that Ga-catalyzed GaAs NW studies relatively narrow temperature (Ts) window around 620 °C Si. In this paper, we have investigated two-step NWs Si (111) substrates by molecular-beam epitaxy. First, optimizing surface oxide, vertically aligned with high yield are obtained at Ts =...
Nanowires (NWs) with radial p-i-n junction have advantages, such as large area and small influence from the surface states, which can lead to highly efficient material use good device quantum efficiency. However, it is difficult make high-quality core-shell NW devices, especially single devices. Here, key factors during growth fabrication process that quality of devices are studied using GaAs(P) photovoltaics an example. By p-doping annealing, ohmic contact achieved on NWs a diameter 50-60...
Sole surface passivation for III–V nanowire photodetectors exhibits limited photoresponse improvement. Consequently, a well-customized contact design is crucial. Here, GaAs nanowire-based metal-semiconductor-metal via treatment and interfacial optimization are reported. The strategy inhibits the recombination and, importantly, effectively reduces Fermi-level pinning effect by redistribution of states. It leads to Schottky barrier height reduced from ∼0.63 ∼0.36 eV at Ni/GaAs contact....
Self-catalyzed AlGaAs nanowires (NWs) and NWs with a GaAs quantum dot (QD) were monolithically grown on Si(111) substrates via solid-source molecular beam epitaxy. This growth technique is advantageous in comparison to the previously employed Au-catalyzed approach, as it removes Au contamination issues renders structures compatible complementary metal-oxide-semiconductor (CMOS) technology applications. Structural studies reveal self-formation of an Al-rich shell, thicker at NW base thinning...
Abstract To further enhance the performance and understand mechanism of InAs quantum dot (QD) laser under high temperature, both theoretically experimentally it is investigated, effects technique combination direct n‐type doping modulation p‐type doping, namely co‐doping, in active region for a wide temperature range over 165 °C. Through comparison co‐doped, doped, undoped QD lasers, reveals that co‐doping provides significantly reduced threshold current density across whole robust...
One of the nanowire (NW) characteristics is its preferred elongation direction. Here, we investigated impact Si substrate crystal orientation on growth direction GaAs NWs. We first studied self-catalyzed NW (111) and (001) substrates. SEM observations show NWs are grown along four <111> directions without preference one or some them. This non-preferential morphologically in contrast to extensively reported vertical propose a model based initial condition an ideal Ga droplet formation...
Abstract For the development of InAs/InP quantum dot (QD) lasers for 1.55 μ m telecom wavelength, there are two main challenges: (1) morphological preference dashes over QDs, and (2) generally poor size uniformity QDs (dashes). This study addresses issues, in synchronous, by demonstrating improved optical properties at room temperature with excellent reproducibility. A high-density (∼4 × 10 cm −2 ) dot-like morphology was initially attained via adjusting growth parameters, albeit a large...
The integration of optically active III–V and electronic-suitable IV materials on the same nanowire could provide a great potential for combination photonics electronics in nanoscale. In this Letter, we demonstrate growth GaAs/Ge core–shell nanowires Si substrates by molecular beam epitaxy investigate radial axial Ge GaAs detail. High-quality with smooth side facets dislocation-free, sharp interfaces are achieved. It is found that low shell temperature leads to smoother facets, while higher...
We report systematic study of growth self-assembled InAs quantum dots (QDs) on GaAs substrate at various temperatures with and without exposure bismuth surfactants. Results show that the coalescence amongst QDs is considerably inhibited by flux during in temperature range from 475 to 500 °C, leading improved dot uniformity a modified density. The mechanism suppression effect surfactants strain-induced islanding through inhibiting indium adatom mobility evaporation rate surface kinetically...
We report the structure and magnetic properties of (In,Mn)As based core-shell nanowires grown on Si (111) by molecular-beam epitaxy. Compared to core InAs nanowire with a flat side facet consistent diameter, shows rough sidewall an inverse tapered geometry. X-ray diffraction, transmission electron microscopy energy-dispersive x-ray spectroscopy show that is formed facets mixture wurtzite zinc-blende structures. Two ferromagnetic transition temperatures from measurement data are observed: one...
The electronic rendition of the Hanle effect, which is interpreted as ensemble dephasing a spin accumulation in semiconductor under perpendicular magnetic field, has been one most widely utilized and effective methods measuring lifetime, accumulation, transport semiconductors. However, origin magnetoresistance three-terminal (3T) setup intensively questioned both theoretically experimentally; this contrast to nonlocal four-terminal (NL-4T) measurement, accepted reflecting its spatial decay...
Abstract In this work, we investigate the epitaxial growth of InAs quantum dots (QDs) on Ge substrates. By varying parameters temperature, deposition thickness and rate InAs, high density (1.2 × 10 11 cm −2 ) self-assembled QDs were successfully epitaxially grown substrates by solid-source molecular beam epitaxy capped layers. Pyramid- polyhedral-shaped embedded in matrices revealed, which are distinct from lens- or truncated pyramid-shaped InAs/GaAs InAs/Si systems. Moreover, with a 200 nm...
For self-catalyzed nanowires (NWs), reports on how the catalytic droplet initiates successful NW growth are still lacking, making it difficult to control yield and often accompanying a high density of clusters. Here, we have performed systematic study this issue, which reveals that effective V/III ratio at initial stage is critical factor governs yield. To initiate growth, should be enough allow nucleation extend entire contact area between substrate, can elevate off but not too in order...
The spin lifetime and Hanle signal amplitude dependence on bias current has been investigated in insulating Al0.3Ga0.7As:Si using a three-terminal effect geometry. amplitudes of the signals are much larger for forward than reverse bias, although lifetimes found statistically equivalent. resistance-area product shows strong increase with small until 150 μA, beyond which weak is observed. diminish substantially increasing current. accumulation only moderately temperature from 5 K to 30 K.