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Single crystal
About: Single crystal is a research topic. Over the lifetime, 59617 publications have been published within this topic receiving 870828 citations.
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TL;DR: Low-energy electron microscopy enables controlled synthesis and characterization of (large) single-crystal borophene on metal substrates and substantiates the idea of boran allotrope as a model for development of artificial 2D materials.
Abstract: Borophene, a theoretically proposed two-dimensional (2D) boron allotrope1–3, has attracted much attention4,5 as a candidate material platform for high-speed, transparent and flexible electronics6–9. It was recently synthesized, on Ag(111) substrates10,11, and studied by tunnelling and electron spectroscopy12. However, the exact crystal structure is still controversial, the nanometre-size single-crystal domains produced so far are too small for device fabrication and the structural tunability via substrate-dependent epitaxy is yet to be proven. We report on the synthesis of borophene monitored in situ by low-energy electron microscopy, diffraction and scanning tunnelling microscopy (STM) and modelled by ab initio theory. We resolved the crystal structure and phase diagram of borophene on Ag(111), but found that the domains remain nanoscale for all growth conditions. However, by growing borophene on Cu(111) surfaces, we obtained large single-crystal domains, up to 100 μm2 in size. The crystal structure is a novel triangular network with a concentration of hexagonal vacancies of η = 1/5. Our experimental data, together with first principles calculations, indicate charge-transfer coupling to the substrate without significant covalent bonding. Our work sets the stage for fabricating borophene-based devices and substantiates the idea of borophene as a model for development of artificial 2D materials. Low-energy electron microscopy enables controlled synthesis and characterization of (large) single-crystal borophene on metal substrates.
240 citations
TL;DR: In this paper, a graphite-like hexagonal structure with a larger lattice constant compared to bulk-like wurtzite AlN was shown to have a reduced energy bandgap for hexagonal AlN.
Abstract: Ultrathin (sub-monolayer to 12 monolayers) AlN nanosheets are grown epitaxially by plasma assisted molecular beam epitaxy on Ag(111) single crystals. Electron diffraction and scanning tunneling microscopy provide evidence that AlN on Ag adopts a graphite-like hexagonal structure with a larger lattice constant compared to bulk-like wurtzite AlN. This claim is further supported by ultraviolet photoelectron spectroscopy indicating a reduced energy bandgap as expected for hexagonal AlN.
239 citations
TL;DR: An ingenious space-limited inverse temperature crystallization method is first demonstrated to the in situ synthesis of 120 cm2 large-area CH3 NH3 PbBr3 crystal film on fluorine-doped tin oxide (FTO) glass, which enables a broad linear response range of 10-4 -102 mW cm-2 and high narrow response under low bias -1 V.
Abstract: Organometal trihalide perovskites have been attracting intense attention due to their enthralling optoelectric characteristics. Thus far, most applications focus on polycrystalline perovskite, which however, is overshadowed by single crystal perovskite with superior properties such as low trap density, high mobility, and long carrier diffusion length. In spite of the inherent advantages and significant optoelectronic applications in solar cells and photodetectors, the fabrication of large-area laminar perovskite single crystals is challenging. In this report, an ingenious space-limited inverse temperature crystallization method is first demonstrated to the in situ synthesis of 120 cm2 large-area CH3 NH3 PbBr3 crystal film on fluorine-doped tin oxide (FTO) glass. Such CH3 NH3 PbBr3 perovskite crystal film is successfully applied to narrowband photodetectors, which enables a broad linear response range of 10-4 -102 mW cm-2 , 3 dB cutoff frequency (f 3 dB ) of ≈110 kHz, and high narrow response under low bias -1 V.
239 citations
TL;DR: In this paper, the lattice parameters of the poly(tetramethylene succinate) (PBS) were determined from the electron diffraction patterns of the single crystals and stretched films.
Abstract: Crystals of an aliphatic polyester, poly(tetramethylene succinate) (PBS) are investigated using transmission electron microscopy. Single crystals grown from a 0.01 wt % dichlorobenzene solution show a terrace-like morphology above 65 °C and a leaflike one at lower temperatures. The molecules are packed perpendicular to the basal plane of the single crystals, and twin crystals with a (110) twin plane are frequently observed. The thickness of the single crystal lamellae increases smoothly with increasing crystallization temperature. Lattice parameters of the PBS crystal in the monoclinic unit cell are determined from the electron diffraction patterns of the single crystals and stretched films as a = 0.523 nm, b = 0.908 nm, c = 1.079 nm, and β = 123.87°. The dimension of the c-axis is shorter than the value calculated from a fully extended chain conformation, as has already been found for other aliphatic polyesters. Two types of negative spherulites are observed according to growth temperature.
238 citations
TL;DR: In this paper, single crystals of Li13Nd(GeO4)4 were grown by the Czochralski method and the unit cell dimensions and the crystal system were determined by an X-ray diffraction method.
Abstract: In this paper, single crystals of Li13Nd(GeO4)4 are grown by the Czochralski method. The unit cell dimensions and the crystal system are determined by an X-ray diffraction method. The principal refractive indices, na, nb and nc and the temperature dependence of birefringences, nc-nb, nc-na and na-nb, over the temperature range from room temperature to 500degC are measured. A fluorescence spectrum at around 1.06 µm is observed, and strong fluorescence is detected.
238 citations