High performance solar-blind deep ultraviolet photodetectors viaβ-phase(In_(0.09)Ga_(0.91))_(2)O_(3)single crystalline film

We successfully fabricate a high performanceβ-phase(In_(0.09)Ga_(0.91))_(2)O_(3)single-crystalline film deep ultraviolet(DUV)solar-blind photodetector.The 2-inches high crystalline quality film is hetero-grown on the sapphire substrates using the plasma-assisted molecular beam epitaxy(PA-MBE).The smooth InGaO single crystalline film is used to construct the solar-blind DUV detector,which utilized an interdigitated Ti/Au electrode with a metal-semiconductor-metal structure.The device exhibits a low dark current of 40 pA(0 V),while its UV photon responsivity exceeds 450 A/W(50 V)at the peak wavelength of 232 nm with illumination intensity of 0.21 m W/cm^(2)and the UV/VIS rejection ratio(R232 nm/R380 nm)exceeds 4×10^(4).Furthermore,the devices demonstrate ultrafast transient characteristics for DUV signals,with fast-rising and fast-falling times of 80 ns and 420 ns,respectively.This excellent temporal dynamic behavior can be attributed to indium doping can adjust the electronic structure of Ga_(2)O_(3)alloys to enhance the performance of InGaO solar-blind detectors.Additionally,a two-dimensional DUV scanning image is captured using the InGaO photodetector as a sensor in an imaging system.Our results pave the way for future applications of two-dimensional array DUV photodetectors based on the large-scale InGaO heteroepitaxially grown alloy wide bandgap semiconductor films.

Dispersion of exciton-polariton based on ZnO/MgZnO quantum wells at room temperature

We report observation of dispersion for coupled exciton-polariton in a plate microcavity combining with ZnO/MgZnO multi-quantum well (QW) at room temperature. Benefited from the large exciton binding energy and giant oscillator strength, the room-temperature Rabi splitting energy can be enhanced to be as large as 60 meV. The results of excitonic polariton dispersion can be well described using the coupling wave model. It is demonstrated that mode modification between polariton branches allowing, just by controlling the pumping location, to tune the photonic fraction in the different detuning can be investigated comprehensively. Our results present a direct observation of the exciton-polariton dispersions based on two-dimensional oxide semiconductor quantum wells, thus provide a feasible road for coupling of exciton with photon and pave the way for realizing novel polariton-type optoelectronic devices.

Preparation of titanium dioxide-double-walled carbon nanotubes and its application in flexible dye-sensitized solar cells

Titanium dioxide-double-walled carbon nano- tubes （TiO2-DWCNTs） with DWCNTs/TiO2 of 20 wt.% is prepared by a conventional sol-gel method. Doping the TiO2-DWCNTs in TiO2 photoanode, a flexible dye- sensitized solar cell （DSSC） is fabricated. The sample is characterized by scanning electron microscopy, X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FTIR） absorption, ultraviolet-visible spectroscopy （UV- vis） absorption spectra , electrochemical impedance spec- troscopy （EIS） technique and photovoltaic measurement. It is found that adding a certain amount of TiO2-DWCNTs can efficiently decrease the resistance of charge transport, improve dye adsorption. Under an optimal condition, a flexible DSSC contained with 0.50 wt.% TiOz-DWCNTs achieves a light-to-electric energy conversion efficiency of 3.89% under a simulate solar light irradiation of 100 mW. cm^2.

Linear and quadratic damping coefficients of a single module of a very large floating structure over variable bathymetry:Physical and numerical free-decay experiments

The linearity assumption is widely used when acquiring the hydrodynamic coefficients of a floating structure.However,the linear damping is frequently underestimated,especially for the natural frequency.To investigate the sloping seafloor effects on the damping terms of a single module of a semi-submersible Very Large Floating Structure(VLFS),this paper revisits the conventional formulation and further proposes the direct integration method for obtaining the linear and quadratic damping coefficients from free-decay tests.Numerical free-decay simulations of the single module over variable bathymetry are carried out by the CFD numerical tank.Corresponding model tests are also implemented to verify and validate against the numerical solutions.The effects of the sloping seafloor,as well as the water depth,on the hydrodynamic coefficients are investigated based on the validated CFD modeling.Both numerical and experimental results indicate that the acquisition of the linear and quadratic damping coefficients is sensitive to the data-processing and identification approaches.For the case studied in present paper,the identification errors introduced by the conventional method are 1.5%while they are 0.5%using the direct integration method.The quadratic damping coefficient for heave mode decreases about 10.4%when the sloping angle increases from 0 to 6 deg.