Photodetectors with ultrahigh sensitivity based on the composite made with all carbon-based materials consisting of graphite quantum dots (QDs), and two dimensional graphene crystal have been demonstrated. Under light illumination, remarkably, a photocurrent responsivity up to 4 × 107 AW−1 can be obtained. The underlying mechanism is attributed to the spatial separation of photogenerated electrons and holes due to the charge transfer caused by the appropriate band alignment across the interface between graphite QDs and graphene. Besides, the large absorptivity of graphite QDs and the excellent conductivity of the graphene sheet also play significant roles. Our result therefore demonstrates an outstanding illustration for the integration of the distinct properties of nanostructured carbon materials with different dimensionalities to achieve highly efficient devices. Together with the associated mechanism, it paves a valuable step for the further development of all carbon-based, cheap, and non-toxic optoelectronics devices with excellent performance.

We report the first attempt at magnetic manipulation of the photoresponse in a one-dimensional device in which a highly sensitive ultraviolet photodetector, composed of tin dioxide nanowire (SnO 2 NW) and ferromagnetic nickel (Ni) electrodes, has been fabricated and characterized. Surprisingly, as the Ni electrodes were magnetized, the photocurrent gain was greatly enhanced by up to 20 times, which is far beyond all of the previously reported enhancement factors for functionalized NW photodetectors. The underlying mechanism enabling the enhanced gain is attributed to both oxygen molecules adsorbed and surface band-bending effects due to the migration of electrons to the surface of SnO 2 NW caused by the magnetic field of ferromagnetic electrodes. The novel approach presented here can provide a new route for the creation of highly efficient optoelectronic devices based on the coupling between ferromagnetic materials and nanostructured semiconductors.

Resistive switching is observed in a single SnO2 nanowire device with two back-to-back Schottky diodes. The underlying mechanism can be well interpreted by the switchable diode effect, which is caused by tunable Schottky barrier heights due to the drift of charged defects induced by external electrical field. A resistance window of more than 3 orders of magnitude has been achieved. The device also shows excellent performance in endurance and retention time. Additionally, a very small current under negative bias is observed, which can avoid the sneaking current induced in the nearby devices. Due to the greatly reduced device size, power consumption, and inherent nature of Schottky diode, the work presented here should be useful for the development of high density circuitries.

The high sensitivity of photodetector in the UV range based on the composite consisting of a single SnO(2) nanowire and NiO nanoparticles has been demonstrated. The underlying mechanism is attributed to the formation of p-NiO and n-SnO(2) heterojunction on the nanowire surface. The enhanced space charge region owing to the existence of p-n heterojunction increases the surface electric field, which will improve the separation of photogenerated electrons and holes, and the photoresponse gain will be greatly enhanced. This work shows a new approach that by decorating suitable p-type nanoparticles on n-type nanowires, the photoresponse gain can be enhanced drastically. Our result should be useful for creating novel high efficiency photodetectors.