Herein, we demonstrate the ultraviolet (UV) light activated high-performance room-temperature NO gas sensor based on nitrogen-doped graphene quantum dots (NGQDs)decorated TiO 2 hybrid structure. TiO 2 employed in the form of {001} facets exposed rectangular nanoplate morphology, which is highly reactive for the adsorption of active oxygen species. NGQD layers are grown on TiO 2 nanoplates by graphitization of precursors via hydrothermal treatment. The decoration of NGQDs on the TiO 2 surface dramatically enhanced the efficiency of gas and carriers exchange, charge carrier separation and transportation, and oxygen vacancies, which eventually improved the sensing performance. At room temperature, the TiO 2 @ NGQDs hybrid structure exhibited a response of 12.0% to 100 ppm NO, which is 4.8 times higher compared to that of pristine TiO 2 nanoplates. The response of TiO 2 @NGQDs hybrid structure is further upgraded by employing the ultraviolet light illumination and manipulating the operating temperature. Under the UV (λ = 365 nm) illumination at room temperature, the hybrid structure response escalated to ∼31.1% for 100 ppm NO. On the other hand, the tailoring of working temperature yielded a response of ∼223% at an optimum operating temperature of 250 °C. The NO gas-sensing mechanism of TiO 2 @NGQDs nanoplate's hybrid structure sensors under UV illumination and different working temperatures is discussed.

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Growth mode and structural properties of GaSb layers grown on silicon substrate by molecular beam epitaxy method are investigated by transmission electron microscopy. It is found that the GaSb grows to three-dimensional islands and grains are tilted to reduce a lattice mismatch through twin boundaries when they are directly grown on Si substrate. A low-temperature (LT) AlSb buffer plays a key role in transferring the growth mode from a three-dimensional island to a layer-by-layer structure. When the LT AlSb layer is used as a buffer, 90° misfit dislocations, with the Burgers vector b of 1∕2a⟨110⟩, are observed on the interface.

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