We report a theoretical analysis of the electronic, optical, and mechanical properties of zinc-blende GaP semiconductor material. High-temperature impact on the interesting features has been reported. The temperature dependence of sound velocity and phonon frequencies of GaP has been determined. The pseudopotential technique has been used in our study. The current study can help in our comprehension of how temperature affects the electronic characteristics of GaP material. Our findings show generally a good accordance with the experiment. The prediction properties could be used in optoelectronic applications in the high-temperature range.

In this paper, Cd1-xZnxS thin films were prepared by chemical bath deposition (CBD), and the effects of different zinc doping content on the morphological structure and optical properties of Cd1-xZnxS buffer layers are systematically discussed. The experimental results show that in the deposition process of different substrates, the crystal structure of the film is all hexagonal, and when the concentration of zinc sulfate (ZnSO4) precursor is varied from 0 to 0.025 M, the films are uniform and dense. With the increase of zinc content, the X-ray diffraction (XRD) peak of the films shifted behind that of CdS film (002). It showed 70% to 90% transmittance in the visible region and the optical band gap increased gradually. The band gap value of the films obtained ranged from 2.43 eV to 3.01 eV. It shows the potential feasibility of its application to photovoltaic devices.

We theoretically study the evolution of dark solitons in the biased photorefractive-photovoltaic crystal by using beam propagation method (BPM). We find that when the absolute value of the extra bias field is less than the photovoltaic field, the dark screening-photovoltaic (SP) solitons can be observed. The initial width of the dark notch at the entrance face of the crystal is a key parameter for generating an sequence of dark coherent solitons. If the initial width of the dark notch is small, only a fundamental soliton or Y-junction soliton pair is generated. When the initial width of the dark notch is increased, the dark notch tends to split into an odd (or even) number of multiple dark solitons, which re-alizes a progressive transition from the low-order solitons to a sequence of higher-order solitons.

With reducing the absorber layer thickness and processing temperature, the recombination at the back interface is se-vere, which both can result in the decrease of open-circuit voltage and fill factor. In this paper, we prepare Al2O3 by atomic layer deposition (ALD), and investigate the effect of its thickness on the performance of Cu(In,Ga)Se2 (CIGS) solar cell. The device recombination activation energy (EA) is increased from 1.04 eV to 1.11 eV when the thickness of Al2O3 is varied from 0 nm to 1 nm, and the height of back barrier is decreased from 48.54 meV to 38.05 meV. An effi-ciency of 11.57 % is achieved with 0.88-μm-thick CIGS absorber layer.

The UV photorefractive properties of near-stoichiometric LiNbO3 single crystal are found to be significantly enhanced com-pared with the congruent one at 325 nm. The temperature dependence of the band edge of near-stoichiometric LiNbO3 crystal is investigated. Significant thermal-induced spectral shift in band gap which obeys the Bose-Einstein expression is observed, and the fundamental band gap at zero absolute temperature is found to be much larger than the congruent one. New absorp-tion bands near the UV band edge which are much stronger in the near-stoichiometric LiNbO3 than those in the congruent LiNbO3 crystal show up at temperatures lower than ~400 K. Note that the UV photorefractivity is enhanced in SLN, which has exactly the same tendency as the absorption strength.

The growth of Na5Lu9F32 single crystals doped with Cr3+ ions in 0.1 mol%, 0.2 mol% and 0.5 mol% concentrations by Bridgman method was reported. The optical absorption and luminescence spectra decisively demonstrate that the Cr dopant enters Na5Lu9F32 as Cr3+. Fluorescence emission at wavelengths of 418 nm, 444 nm, 653 nm and 678 nm can be observed under the excitation of 372 nm and the fluorescence lifetime at 418 nm was measured to be ~10.31 μs. The possible crystal sites for Cr3+ ions in Na5Lu9F32 single crystal were discussed, and the lattice parameter Dq, Racach parameters B and C were estimated.

In this paper, an accurate frequency offset estimator is investigated in the intermediate frequency for the satellite-based automatic identification system (AIS) signals. Using Gaussian minimum shift keying (GMSK) modulation for trans-mission, the AIS signal is shown to be a plane wave with the modulated phase information and carrier frequency re-sulting from the Doppler effects. Hence, the phase information can be eliminated with a re-modulated signal, and the frequency offset can be estimated by the ratio of the maximum spectral amplitude and its neighbor spectral amplitude based on the fast Fourier transformation (FFT) interpolation. The estimator has low complexity, and it is easy to im-plement. Computer simulations are used to assess the performance of the estimator.

Taking into consideration the aperture averaging, the system performance of a point-to-multipoint free space optical (FSO) system for various multiuser diversity scheduling schemes is studied over exponentiated Weibull (EW) fading channels. The selection principles of greedy scheduling (GS), selective multiuser diversity scheduling (SMDS), proportional fair scheduling (PFS) and selective multiuser diversity scheduling with exponential rule (SMDS-ER) schemes are introduced and compared on the basis of time-varying behavior of turbulence channel fading in the present system. The analytical average capacity ex-pressions for the GS and SMDS schemes are derived, respectively. Then, the relative capacity simulations for PFS and SMDS-ER schemes are also provided over EW fading channels with the binary phase shift keying (BPSK) modulation. The results show that the GS scheme obtains the maximum average capacity at the cost of the fairness of users. The SMDS-ER receives the minimum capacity, but it guarantees the fairness of users. The SMDS and PFS schemes can get balance between capacity and fairness. This study can be used for FSO system design.

Ag3PO4 microparticles (MPs) were prepared through a facile chemical precipitation route and using silver acetate (AgAc) as metal salt. The effect of annealing temperature (Ta) and time (τa) on the actual photocatalytic (PC) activity of Ag3PO4 MPs is investigated. The optimal annealing parameters are Ta of 400 °C and τa of 90 min. The enhanced PC activity by annealing at 400 °C is ascribed to the increase of electron mobility. Besides, an Ag3PO4 photoelectrode was fabricated through a drop-coating deposition route, which demonstrates a photocurrent density of 80 μA/cm2 and ac-ceptable stability. The n-type conduction behavior of Ag3PO4 is verified by a Mott-Schottky (M-S) plot.

We demonstrate tandem organic light-emitting diodes (TOLEDs) with excellent performance using Al and MoO3 buffer-modified C60/pentacene as charge generation layer (CGL). Al and MoO3 were used as the electron and hole in-jection layers of C60/pentacene CGL, respectively. Green phosphorescence TOLEDs with the structure of ITO/NPB/mCP:Ir(ppy)3/TPBi/Al/C60/pentacene/MoO3/NPB/mCP:Ir(ppy)3/TPBi/Cs2CO3/Al were fabricated. The re-sults show that the inserted Al and MoO3 can effectively increase the charge injection capacity of organic CGL, re-sulting the improvement of luminance and current efficiency of TOLEDs. The turn-on voltage of TOLEDs is much lower than that of single-unit device, and the current efficiency is more than 2 times larger than that of the single-unit device. TOLEDs can exhibit excellent photoelectric performance when the thicknesses of Al, C60, pentacene and MoO3 are 3 nm, 15 nm, 25 nm and 1 nm, respectively. The maximum luminance and current efficiency are 7 920.0 cd/m2 and 16.4 cd/A, respectively. This work is significant to build new CGL structures for realizing high-performance TOLEDs.

In this work,indium nitride (InN) films were successfully grown on porous silicon (PS) using metal oxide chemical vapor deposition (MOCVD) method. Room temperature photoluminescence (PL) and field emission scanning electron microscopy (FESEM) analyses are performed to investigate the optical, structural and morphological properties of the InN/PS nanocomposites. FESEM images show that the pore size of InN/PS nanocomposites is usually less than 4 μm in diameter, and the overall thickness is approximately 40 μm. The InN nanoparticles penetrate uniformly into PS layer and adhere to them very well. Nitrogen (N) and indium (In) can be detected by energy dispersive spectrometer (EDS). An important gradual decrease of the PL intensity for PS occurs with the increase of oxidation time, and the PL intensity of PS is quenched after 24 h oxidization. However, there is a strong PL intensity of InN/PS nanocomposites at 430 nm (2.88 eV), which means that PS substrate can influence the structural and optical properties of the InN, and the grown InN on PS substrate has good optical quality.

In this work,a two-photon polymerization (2PP) processing device was built using the femtosecond laser, and femtosecond laser direct writing was performed on SU-8 photoresist. Due to the 2PP effect of the photoresist caused by the femtosecond laser, the polymeric line with size less than the focal spot size is obtained. Based on the Raman spectroscopy characterization of SU-8 polymer before and after 2PP, we research the dynamic process of femtosecond laser induced 2PP. In Raman spectra, some scattering peaks with large intensity variation, such as 1 108 cm-1 and 1 183 cm-1, indicate that the asymmetric stretching vibration of C-O-C bond in SU-8 polymer is increased. By comparison, we can find that 2PP only affects the light absorption of initiator, but does not affect the monomer polymerization. It is helpful to understand the interaction of photoresist and femtosecond laser, and plays an important role in quantitatively controlling the polymerization degree of SU-8 polymer and improving the processing resolution of 2PP.

We report rigorous coupled-wave analysis (RCWA) method to non-destructively characterize the domain structure of periodically poled lithium niobate (PPLN) crystal. The strong light diffraction effect is achieved by applying a proper external voltage. We can observe reversed domain pattern and employ the detected diffraction intensity to optimally fit the result of RCWA based on least square method. Compared with conventional scalar diffraction theory, more accurate domain structure parameters with accuracies of 0.05 ?倕 m and 0.005 for the period and duty cycle are obtained respectively. It is proved that accurate, real-time and nondestructive characterization can be realized via this method.

Tm3+ doped Na5Lu9F32 single crystal with high optical quality was grown by an improved Bridgman method. The Judd-Ofelt intensity parameters Ωt (t=2, 4, 6) were calculated according to the measured absorption spectra and physical-chemical properties of the obtained Na5Lu9F32 single crystal. The stimulated emission cross-section of the 3F4→3H6 transition (~1.8 μm) is 0.35×10-20 cm2 for Tm3+ doped Na5Lu9F32 single crystal. The emission spectra under the excitation of 790 nm laser diode (LD) and fluorescence lifetime at 1.8 μm were measured to reveal the fluorescence properties of Tm3+ doped Na5Lu9F32 single crystal. The research results show that the Tm3+ doped Na5Lu9F32 single crystal has larger stimulated emission cross-section compared with other crystals. All these spectral properties suggest that this kind of Tm3+doped Na5Lu9F32 crystal with high physical-chemical stability and high-efficiency emission at 1.8 μm may be used as potential laser materials for optical devices.

Tm3+doped Na5Lu9F32single crystal with high optical quality was grown by an improved Bridgman method. The Judd-Ofelt intensity parameters Ωt(t=2, 4, 6) were calculated according to the measured absorption spectra and physical- chemical properties of the obtained Na5Lu9F32single crystal. The stimulated emission cross-section of the 3F4→3H6transition (~1.8 μm) is 0.35×10-20cm2for Tm3+doped Na5Lu9F32single crystal. The emission spectra under the excitation of 790 nm laser diode (LD) and fluorescence lifetime at 1.8 μm were measured to reveal the fluorescence properties of Tm3+doped Na5Lu9F32single crystal. The research results show that the Tm3+doped Na5Lu9F32single crystal has larger stimulated emission cross-section compared with other crystals. All these spectral properties suggest that this kind of Tm3+doped Na5Lu9F32crystal with high physical-chemical stability and high-efficiency emission at 1.8 μm may be used as potential laser materials for optical devices.

WO3oxides with relatively high phonon energy and different concentrations were introduced into the Nd3+-doped tellurite- based glasses of TeO2-ZnO-Na2O to improve the 1.32 μm band fluorescence emission. The absorption spectra, Raman spectra, 1.32 μm band fluorescence spectra and differential scanning calorimeter (DSC) curves were measured, together with the Judd-Ofelt intensity parameters, stimulated emission and gain parameters were calculated to evaluate the effects of WO3amount on the glass structure and spectroscopic properties of 1.32 μm band fluorescence. It is shown that the introduction of an appropriate amount of WO3oxide can effectively improve the 1.32 μm band fluorescence intensity through the enhanced multi-phonon relaxation (MPR) processes between the excited levels of Nd3+. The results indicate that the prepared Nd3+-doped tellurite glass with an appropriate amount of WO3oxide is a potential gain medium applied for the O-band broad and high-gain fiber amplifier.

The Yb3+-doped silica glass was prepared by the SiCl4 hydrolysis doping and powder melting technology based on high frequency plasma. The absorption and emission characteristics of the Yb3+-doped silica glass are studied at room temperature. The integrated absorption cross section, stimulated emission cross section and fluorescence lifetime are calculated to be 8.56×104pm3, 1.39 pm2and 0.56 ms, respectively. The Yb3+-doped microstructure fiber (MSF) was also fabricated by using the Yb3+-doped silica glass as fiber core. What’s more, the laser properties of the Yb3+-doped MSF are studied.

In this paper, the anisotropic etching process of Si(100) wafers in tetramethyl ammonium hydroxide (TMAH) solution with isopropyl alcohol (IPA) is investigated in detail. An inverted trapezoidal pattern is developed. A series of experiments are performed by changing TMAH concentration, IPA concentration, etching temperature and etching time. The structure of inverted trapezoidal patterns and roughness of the bottom surface are characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results show that with TMAH concentration increases, the roughness of bottom surface will decrease. The addition of IPA into TMAH solution improves the morphology of the bottom surface significantly. Low temperature is beneficial to get a smooth bottom surface. Furthermore, etching time can change the bottom surface roughness. A model is proposed to explain the etching processes. The hillock area ratio of the bottom surface has the same tendency as the etching area ratio. Finally, smooth silicon inverted trapezoidal patterns are obtained for epitaxial growth of GaN-based light emitting diode (LED) devices.

The doping content of Mg plays an important role in the crystalline structure and morphology properties of Zn1-xMgxO thin films. Here, using radio-frequency magnetron sputtering method, we prepared Zn1-xMgxO thin films on single crystalline Si(100) substrates with a series of x values. By means of X-ray diffraction (XRD) and scanning electron microscope (SEM), the crystalline structure and morphology of Zn1-xMgxO thin films with different x values are investigated. The crystalline structure of Zn1-xMgxO thin film is single phase with x0.3, and hexagonal and cubic structures will coexist in Zn1-xMgxO thin films with higher x values. Especially with lower x values, a shoulder peak of 35.1° appearing in the XRD pattern indicates a double-crystalline structure of Zn1-xMgxO thin film. The crystalline quality has been improved and the inner stress has been released, after the Zn1-xMgxO thin films were annealed at 600 °C in vacuum condition.

In this work, surface enhanced Raman spectroscopy (SERS) substrates with Ag nanoparticles (NPs) decorated Co3O4nanowires (NWs) grafted on the three-dimensional (3D) network architecture of Ni foam (denoted as Ag-NP@Co3O4- NW/Ni-foam) arrays are manufactured. In the experiment, the hierarchical Ag-NP@Co3O4-NW/Ni-foam arrays exhibit strong SERS activity due to the higher density of the “hot spots” created from the large quantities of neighboring Ag NPs. Using this hierarchical 3D SERS substrates, the crystal violet (a banned drug of aquaculture) with concentration down to 10-14mol/L can be detected, which shows potential application in SERS-based rapid trace-level detection of harmful food additives.