Investigations of photoelectrical properties of ZnO films are important scientific task for designing UV detectors for various applications. We report the positive role of nitrogen doping in increasing photoresponsivity of ZnO:N‐based detectors. It is suggested that nitrogen slightly deteriorates the structural quality of ZnO films and compensates intrinsic defects that increase photoresponsivity. Also, the spectral response of Ni/ZnO:N/n+‐Si structures at different biases were considered.
We demonstrate that the electrical quality of junctions fabricated in lattice-mismatched In0.75Ga0.25As on InP grown by molecular beam epitaxy can be improved with the addition of in situ anneals in the buffer layer that separates the substrate from the In0.75Ga0.25As device layers. Near infrared photodetectors fabricated using this material had dark current densities of approximately 2.5 mA/cm2 at a reverse bias of 1 V, which is more than one order of magnitude smaller than commercially available photodetectors grown using vapor phase epitaxy. Transmission electron microscopy revealed that dislocations due to the lattice mismatch between the substrate and the epitaxial layer are confined primarily to the buffer layer for all samples studied. No significant differences in x-ray diffraction spectra or dislocation distribution were observed on samples with and without in situ annealing. Atomic force microscopy indicated that all samples had a crosshatch pattern, and that the average surface roughness of the sample that contained in situ anneals is a factor of three greater than the sample without in situ anneals. 相似文献
Three acceptor–acceptor (A–A) type conjugated polymers based on isoindigo and naphthalene diimide/perylene diimide are designed and synthesized to study the effects of building blocks and alkyl chains on the polymer properties and performance of all‐polymer photoresponse devices. Variation of the building blocks and alkyl chains can influence the thermal, optical, and electrochemical properties of the polymers, as indicated by thermogravimetric analysis, differential scanning calorimetry, UV–vis, cyclic voltammetry, and density functional theory calculations. Based on the A–A type conjugated polymers, the most efficient all‐polymer photovoltaic cells are achieved with an efficiency of 2.68%, and the first all‐polymer photodetectors are constructed with high responsivity (0.12 A W?1) and detectivity (1.2 × 1012 Jones), comparable to those of the best fullerene based organic photodetectors and inorganic photodetectors. Photoluminescence spectra, charge transport properties, and morphology of blend films are investigated to elucidate the influence of polymeric structures on device performances. This contribution demonstrates a strategy of systematically tuning the polymeric structures to achieve high performance all‐polymer photoresponse devices. 相似文献
Multielemental systems enable the use of multiple degrees of freedom for control of physical properties by means of stoichiometric variation. This has attracted extremely high interest in the field of 2D optoelectronics in recent years. Here, for the first time, multilayer 2D ternary Ta2NiSe5 flakes are successfully fabricated using a mechanical exfoliation method from chemical vapor transport synthesized high quality bulk and the optoelectronic properties are systematically investigated. Importantly, a high responsivity of 17.21 A W?1 and high external quantum efficiency of 2645% are recorded from an as‐fabricated photodetector at room temperature in air; this is superior to most other 2D materials‐based photodetectors that have been reported. More intriguingly, a usual sublinear and an unusual superlinear light‐intensity‐dependent photocurrent are observed under air and vacuum, respectively. These excellent and special properties make multilayer ternary Ta2NiSe5 a highly competitive candidate for future infrared optoelectronic applications and an interesting platform for photophysics studies. 相似文献
