Preparation and photodetection performance of high crystalline quality and large size β-Ga_(2)O_(3)microwires

Ultrawide band gap semiconductors are promising solar-blind ultraviolet(UV)photodetector materials due to their suitable bandgap,strong absorption and high sensitivity.Here,β-Ga_(2)O_(3)microwires with high crystal quality and large size were grown by the chemical vapor deposition(CVD)method.The microwires reach up to 1 cm in length and were single crystalline with low defect density.Owing to its high crystal quality,a metal–semiconductor–metal photodetector fabricated from a Ga_(2)O_(3)microwire showed a responsivity of 1.2 A/W at 240 nm with an ultrahigh UV/visible rejection ratio(R_(peak)/R_(400 nm))of 5.8×10^(5),indicating that the device has excellent spectral selectivity.In addition,no obvious persistent photoconductivity was observed in the test.The rise and decay time constants of the device were 0.13 and 0.14 s,respectively.This work not only provides a growth method for high-quality Ga_(2)O_(3)microwires,but also demonstrates the excellent performance of Ga_(2)O_(3)microwires in solar-blind ultraviolet detection.

Increasing ZnO Growth Rate by Modifying Oxygen Plasma Conditions in Plasma-Assisted Molecular Beam Epitaxy

The authors report that the growth rate of ZnO can be significantly increased by modifying the oxygen plasma conditions in plasma-assisted molecular beam epitaxy. Both the aperture diameter and the distance between the plasma source and the substrate affect the growth rate and the quality of the ZnO films. A short source to substrate distance is essential in achieving higher growth rate, which is explained by reduced chance of oxygen atom collisions to accommodate the short oxygen mean free path at high background pressure. At a shorter source to substrate distance, the growth rate is higher with a larger aperture diameter. The quality of the ZnO thin films grown under different conditions is assessed by x-ray diffraction and room-temperature photoluminescence measurements.

Review on carbon dots:Synthesis and application in biology field

As a multifunctional fluorescent nanomaterial, carbon dots (CDs) not only have small size, stable chemical properties, excellent photoluminescence characteristics, but also exhibit good biocompatibility and low toxicity. It has attracted considerable attention in the field of nanotechnology and biological science. CDs contain abundant functional groups on the surface, which not only retain part of the properties of raw materials, but also may have new photoelectric, catalytic, biomedical, and other functions. In this review, we systematically summarize the synthesis methods, modifications, optical properties, and main biological functions of CDs in recent years. The application of functionalized modified CDs in biological detection, biological imaging, photodynamic therapy, photothermal therapy, targeted therapy, drug delivery, gene delivery, protein delivery, and other biomedical fields is introduced. The latest progress of CDs with its own biomedical function in antioxidant, anti-pathogen, and disease treatment is summarized. Finally, we discuss some problems in the practical application of CDs and look forward to the future development trend of self-functional CDs combined with surface modification to achieve multimodal treatment of diseases.