•Radial artery pulse sensor was fabricated using flexible graphene-coated fiber.•Periodic pulse wave and subtle wave changes were successfully detected.•The radial artery augmentation index could be accurately calculated from the obtained waveforms.We design and fabricate a facile, portable and scalable radial artery pulse sensor, then successfully employ it into the analysis of personalized health status. The sensing component comes from a stretchable graphene-coated fiber which shows good linearity and sensitivity to the tensile strain. Further combined with the smart structure of the sensor, the precise detection of periodic pulse wave and the wave changes induced by exercise and disease becomes avaiable and repeatable. In particular, the obtained single waveform contains almost all the characteristics the medical analysis requires, from which we can evaluate the cardiovascular risk factors for citizen medicine, home healthcare and disease prevention.

III–V semiconductor/graphene tubular structures with diameters of 4.5–5.4 μm have been fabricated on a silicon platform by rolling up monolayer CVD graphene together with heteroepitaxial InGaAs/GaAs bilayers. Scanning electron microscopy (SEM) reveals that transferred graphene adheres to the wall of the Si-based InGaAs/GaAs microtube. Micro-Raman spectroscopy measurements show remarkable redshifts of the G and 2D bands of graphene after planar graphene totally rolls up, reflecting that rolled-up graphene is under uniaxial tensile strain and the strain originates from the rolled-up InGaAs/GaAs microtube. We also fabricated GaAs-based III–V semiconductor/graphene tubular structures with diameters of 3.7 and 4.7 μm, respectively, thus finding an approach to graphene strain engineering (i.e., the Raman redshift and tensile strain of rolled-up graphene increase with the decrement of microtube diameter). Obviously, assembling strained graphene with III–V semiconductors in rolled-up form on a Si platform will bring about a variety of Si-based electronic and optical applications in the future.

•Free-standing GaAs/AlGaAs single quantum well (SQW) and InGaAs/GaAs bilayer microtubes have been fabricated by photolithography and chemical etching.•A single PL peak at 824 nm and 870 nm was observed for SQW and bilayer microtubes, in which quantum-confinement-effect (QCE)-induced blue-shift (~46 nm) of GaAs PL peaks could be seen.•Raman measurements demonstrated the two-mode behavior of Al0.3Ga0.7As barrier in SQW for the first time and the red shifting of LO to lower frequencies reflected the compressive strain decrease.Optical properties of free-standing GaAs/AlGaAs single quantum well (SQW) microtubes have been investigated by room-temperature micro-photoluminescence (PL) and Raman measurements, followed by the detailed comparison with the corresponding properties of InGaAs/GaAs bilayer microtubes. Single peaks originating from GaAs SQW (~824 nm) and bulk GaAs (~870 nm) were observed in PL spectra of free-standing SQW and bilayer microtubes, respectively, which clearly shows the quantum-confinement-effect (QCE)-induced blue shift (~46 nm) of GaAs PL peaks. The spectral red-shift (~12 nm) of SQW PL peak due to strain release was confirmed after the as-grown planar rolled up into microtube. For Raman spectra, both GaAs-like and AlAs-like LO phonons of Al0.3Ga0.7As barrier which demonstrated the two-mode behavior were observed for SQW microtubes. Meanwhile, all LO phonon modes of SQW microtube were obviously red-shifted to lower frequencies (~10 cm−1) when compared with SQW planar, reflecting the compressive strain decreases.

Boron-containing GaAsSb/GaAs quantum wells (QWs) with different antimony (Sb) mole fractions were grown by low-pressure metal–organic chemical vapor deposition for the first time. The effects of boron incorporation on the performance of GaAsSb/GaAs QWs are discussed. For samples with low compressive strain, injection of triethylboron can enhance the Sb content and increase the compressive strain, although boron incorporation can lead to a reduction in strain. This effect was less for strained GaAsSb/GaAs QWs, so the compressive strain of these QWs did not vary. Room-temperature photoluminescence emission at 1116 nm with a full-width at half-maximum (FWHM) value of 56 meV was obtained for strained BGaAsSb/GaAs QWs.

Zinc-blende BxAl1−xAs and BxAl1−x−yInyAs alloys have been grown on exactly oriented (0 0 1)GaAs substrates by low pressure metalorganic chemical vapor deposition (LP-MOCVD). The influence of susceptor coating, growth temperature and gas-phase boron mole fraction on boron incorporation into AlAs has been comprehensively investigated. It has been found that boron incorporation into AlAs could be enhanced and the optimal growth temperature range of BxAl1−xAs alloys changed from 580 °C to 610 °C when SiC-coated graphite susceptors were replaced by the non-coated ones. In this study, the maximum boron composition x of 2.8% was achieved for the pseudomorphically strained BxAl1−xAs alloys. AFM measurements show that RMS roughness of BxAl1−xAs alloys increased sharply with the increase of gas-phase boron mole fraction. Raman spectra of BxAl1−xAs alloys show a linear increase of the BAs shift with boron composition x. Based on BAlAs deposition, bulk BxAl1−x−yInyAs (x = 1.9%) quaternary alloy was grown lattice-matched to GaAs successfully. Moreover, 10-period BAlAs/GaAs and BAlInAs/GaAs MQW heterostructures were also demonstrated.Highlights► The influence of graphite susceptor coating on boron incorporation into AlAs has been investigated for the first time. ► Surface morphology revolution and Raman scattered spectra of bulk BxAl1−xAs alloys with boron composition increased have been studied. ► The behaviors of boron incorporation into AlAs and GaAs have been compared. ► Bulk BxAl1−x−yInyAs quaternary alloys have been grown on GaAs substrates for the first time. ► Lattice-matched BxAl1−x−yInyAs (x = 1.9%) alloy and corresponding 10-period BAlInAs/GaAs MQW structure have been demonstrated for the first time.

High quality zinc-blende BxGa1−xAs, BxAl1−xAs, BxGa1−x−yInyAs and relevant MQW structures containing 10-period BGaAs/GaAs and BGaInAs/GaAs have been successfully grown on exactly-oriented (0 0 1)GaAs substrates by low pressure metalorganic chemical vapor deposition (LP-MOCVD). Triethylboron, trimethylgallium, trimethylaluminum, trimethylindium and arsine were used as the precursors. Boron incorporation behaviors have been studied as a function of growth temperature and gas-phase boron mole fraction.In this study, the maximum boron composition (x) of 5.8% and 1.3% was achieved at the same growth temperature of 580 °C for bulk BxGa1−xAs and BxAl1−xAs, respectively. 11 K photoluminescence (PL) peak wavelength of lattice-matched BxGa1−x−yInyAs epilayer with boron composition of about 4% reached 1.24 μm.

Zinc-blende BxGa1−xAs alloys have been successfully grown on exactly oriented (0 0 1)GaAs substrates using triethylboron, trimethylgallium and arsine sources. The growth has been accomplished in a vertical low-pressure metalorganic chemical vapor deposition (LP-MOCVD) reactor. Boron incorporation behaviors have been extensively studied as a function of growth temperature and gas-phase boron mole fraction. The evolution of surface morphology was also observed.The maximum boron composition of 5.8% is obtained at the optimum growth temperature of 580 °C. RMS roughness over the surface area of 1×1 μm2 is only 0.17 nm at such growth conditions. Based on the experimental results, it has been clearly shown that boron incorporation will decrease significantly at higher temperature (>610 °C) or at much lower temperature (⩽550 °C).

The density property of InAs/GaAs quantum dots (QDs) grown by metal-organic chemical vapor deposition (MOCVD) was investigated in detail. The saturation density of InAs/GaAs QDs was experimentally demonstrated. The InAs deposition thickness (InAs coverage) when the saturation density reached was also found. Furthermore, we systemically analyzed the influences of growth temperature and growth rate of InAs/GaAs QDs on the saturation density. Finally, BInAs/GaAs QDs with room-temperature photoluminescence (RT-PL) wavelength of 1320 nm and full width at half maximum (FWHM) of 40 mev were achieved for the first time, and the effects of boron incorporation on InAs/GaAs QDs were studied.Graphical AbstractThe saturation density property of (B)InAs/GaAs quantum dots and the influence of growth temperature and growth rate were investigated. BInAs QDs with wavelength of 1320 nm was achieved and the effect of boron incorporated into QDs was studied.Download full-size imageHighlights► Existence of saturation density of InAs QDs was demonstrated. ► Influence of growth temperature and growth rate on the saturation density was investigated. ► BInAs/GaAs QDs with wavelength of 1320 nm and FWHM of 40 mev were achieved. ► Change of QDs property with different boron incorporation amount was analyzed.

We report near 1.3 μm strong photoluminescence (PL) emission from 5-stacked InAs/GaAs quantum dots (QDs) monolithically grown on Si (1 0 0) substrates with 4° miscut towards [110] direction by metal organic chemical vapor deposition (MOCVD). The metamorphic QD samples on Si were grown by three-step method, in which bottom Al0.8Ga0.2As cladding and GaAs waveguide layers were simultaneously incorporated in order to fabricate Si-based QD light emitting devices later. In particular, the GaAs waveguide layer grown with low and high temperature alternated significantly suppresses the upwards propagating of threading dislocations (TDs) into QD region and flattens the surface for latter adjacent nucleation of QDs. As a result, room-temperature photoluminescence intensity of as-grown Si-based InAs/GaAs QD sample attains 87% of that on GaAs and its PL peak as long as 1280 nm with the full width at half maximum value up to 78 nm (i.e., 60 meV). Our study shows the great opportunity of using MOCVD grown Si-based metamorphic QDs for 1.3 μm band light emitting devices.