Single-stack InAs self-assembled quantum dots (QD) lasers based on InP substrate have been grown by metalorganic vapor phase epitaxy. The narrow ridge waveguide lasers lased up to 260 K in continuous wave operation, and near room temperature in pulsed mode, with emission wavelengths between 1.59 to 1.74 pm. Above 200 K, a very low wavelength temperature sensitivity of 0.09 nm/K was obtained, which is as low as that caused by the refractive index change. Lasing spectra at different temperature revealed that the ground states and the excited states were almost overlapped, and formed a qusi-continuous band due to dot's large size and inhomogeneously broadening. These results will provide guidance for further development of long wavelength InAs QD lasers based on InP substrate.
We synthesized catalyst-free-Ga 2 O 3 nanorods with terminated ultra-sharp tips by heat treating single crystalline GaAs in a chemical vapor deposition (CVD) chamber without introducing a precursor. The unique, straightforward , synthetic route and a possible growth mechanism are discussed to explain the different morphology of the grown nanorods and the ultra-sharp nanostructures. The morphology and structure of the nanorods were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Raman-spectroscopy. The ultra-sharp tips were found to have radii of ∼3-5 nm and were utilized to achieve enhanced field emission. The field emission characteristics demonstrated a turn-on field of 2.1 V m −1 , a threshold electric field of 5.6 V m −1 , and a geometrical field enhancement factor of 3786, making them comparable to nanostructured diamond and highly oriented single wall carbon nanotubes.
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