Xinhua Pan

Electrical and optical properties of phosphorus-doped p-type ZnO films grown by metalorganic chemical vapor deposition

P-doped p-type ZnO thin films have been grown by metalorganic chemical vapor deposition. By modulating the P evaporating temperature, p-type conductivity can be controlled due to the different P content incorporated into the ZnO films. The P-doped p-type ZnO thin films are of high optical quality, as indicated by low-temperature photoluminescence. P-related acceptor state with an energy level of 163 meV is identified from free-to-neutral-acceptor transitions. In addition, x-ray photoelectron spectroscopy confirms that only one chemical bonding state of P exists in the P-doped ZnO thin films.

Honeycomb-like NiO/ZnO heterostructured nanorods: photochemical synthesis, characterization, and enhanced UV detection performance

Honeycomb-like NiO/ZnO heterostructured nanorods (NRs) were fabricated by a simple photochemical deposition method. The morphology of the NiO nanostructures can be rationally tailored by changing the concentration of the solution, reaction time and annealing temperature. A reasonable formation mechanism of the honeycomb-like NiO/ZnO NRs is proposed, which is closely related to the production of OH− in the vicinity of ZnO NRs during the photochemical deposition process. The fabricated NiO/ZnO p–n heterojunction shows a well-defined rectifying characteristic with a turn-on voltage of 0.66 V and a negligible leakage current. Moreover, the UV detection performance increases considerably compared to that of bare ZnO NRs, which is attributed to the change of nanostructure and the extended carrier depletion region near p-NiO/n-ZnO junctions.

Controlled synthesis of spinel ZnFe2O4 decorated ZnO heterostructures as peroxidase mimetics for enhanced colorimetric biosensing

Controlled synthesis of spinel ZnFe2O4 nanoparticle-decorated ZnO nanofiber heterostructures was carried out with regularly varied particle sizes and uniform distribution. The obtained heterostructures possessed enhanced intrinsic peroxidase-like activity, and the activities regularly changed as the sizes of ZnFe2O4 nanoparticles varied. The heterostructures were further applied in sensitive colorimetric biosensing of urine glucose.

A single mesoporous ZnO/Chitosan hybrid nanostructure for a novel free nanoprobe type biosensor.

A novel method of fabricating a free probe type nanoscale biosensor is first demonstrated. A free probe type biosensor based on a single one-dimensional (1D) mesoporous ZnO/Chitosan inorganic-organic hybrid nanostructure is constructed. The as-prepared biosensor exhibited excellent biosensing performance and was stable in solution due to its inorganic-organic hybrid structure. The special mesoporous nanostructure with protuberances favors enzymes loading and enhances electrical communication efficiency. The feasibility of employing a single 1D nanostructure as a separate free nanoprobe for biosensing is demonstrated. This kind of free probe type biosensor will not only provides a new tool for micro-targets detection in microcell and enzymatic studies, but also has the potential to be inserted into single cell or other microorganism for biological studies.

Preparation of p-type ZnMgO thin films by Sb doping method

We report on Sb-doped p-type Zn0.95Mg0.05O thin films grown by pulsed laser deposition. The Sb-doped Zn0.95Mg0.05O films show an acceptable p-type conductivity with a resistivity of 126 � cm, a Hall mobility of 1.71 cm 2 V −1 s −1 and a hole concentration of 2.90 × 10 16 cm −3 at room temperature. Secondary ion mass spectroscopy confirms that Sb has been incorporated into the Zn0.95Mg0.05O films. Guided by x-ray photoemission spectroscopy analysis and a model for large-size-mismatched group-V dopants in ZnO, an SbZn–2VZn complex is believed to be the most possible acceptor in the Sb-doped p-type Zn0.95Mg0.05O thin films. (Some figures in this article are in colour only in the electronic version)

ZnO homojunction UV photodetector based on solution-grown Sb-doped p-type ZnO nanorods and pure n-type ZnO nanorods

A ZnO homojunction UV photodetector based on Sb-doped p-type ZnO nanorods (NRs) and n-type ZnO NRs was fabricated by a low temperature solution method. The fabricated homojunction shows well-defined rectifying characteristics, confirming the p-type conductivity of the Sb-doped ZnO NRs. Moreover, a high UV sensitivity of 3300% and a fast reset time to UV illumination are also achieved.

The enhancement of a self-powered UV photodetector based on vertically aligned Ag-modified ZnO nanowires

A self-powered photoelectrochemical cell-type UV detector has been fabricated using Ag nanoparticle-modified ZnO NWs as an active photoanode and H2O as the electrolyte. The fabricated device shows a high responsivity (0.37 A W−1). The enhancement is attributed to the modification of the structure which enables more effective separation and directional transfer.

Enhanced UV detection performance using a Cu-doped ZnO nanorod array film

A compact Cu-doped ZnO nanorod (NR) array film was synthesized by a facile hydrothermal method and post-annealing process. The obtained ZnO NR array film-based UV photodetectors exhibit not only enhanced UV sensitivity but also faster reset time compared to undoped ZnO NR samples, which are attributed to the trapping and de-trapping of electrons by Cu-related defects.

Self-assemble ZnMn2O4 hierarchical hollow microspheres into self-supporting architecture for enhanced biosensing performance

We demonstrate a facile and scalable approach to fabricate and self-assemble the hierarchical hollow microspheres into self-supporting architecture by naturally grown branches. The supporting branches can afford integrated transport channels and significantly improve the kinetic performance and mechanical stability. Meanwhile, the supported hierarchical microspheres acting as functional cell can provide high active sites, multiple response and suitable environment for immobilizing biomolecules. Different enzymes are immobilized for biosensors. The experiments demonstrate that the effective assembly of hierarchical microspheres into large size ordered architecture by self-supporting branches can significantly enhance the biosensing performance.

Enhanced photoluminescence of nonpolar p-type ZnO film by surface plasmon resonance and electron transfer

Nonpolar oriented Na-doped ZnO films were grown on m-plane sapphire substrates by plasma-assisted molecular beam epitaxy. The films show repeatable p-type conductivity with a hole concentration of about 3.0×10(16) cm(-3) as identified by the Hall-effect measurements. 10-fold enhancement in the near-band-edge (NBE) emission of the nonpolar p-type ZnO by employing Pt nanoparticle surface plasmons has been observed. In addition, the deep level emission has been entirely suppressed. The underlying mechanism behind the enhancement of NBE emission and the quenching of defect emission is a combination of the electron transfer and the resonant coupling between NBE emission and Pt nanoparticle surface plasmons.