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Phosphorus doped ZnO nanoparticles have been synthesized by simple thermal decomposition. By adjusting the concentration of reaction sources, different doping concentrations nanoparticals were obtained and kept wurtzite structure. The EDX and XPS results confirmed P incorporated in ZnO lattice and formed PZn-2VZn complex acceptor. In low temperature PL spectra and temperature dependent PL spectra, the emission peak located at 3.350 eV, 3.310 eV and 3.241 eV could be observed which were attributed to A0X, FA and DAP. Then, the increasing of P-doping concentrations would cause the energy of acceptor bound exciton became lower, and enhance the intensity of FA emission. [ABSTRACT FROM AUTHOR]

We investigated the suitability of aluminum nitride (AlN) for surface passivation and protection of gallium arsenide (GaAs), using a low-temperature passivation method. By varying the plasma power (100, 200 W) during etching, we found that 200 W produced better passivation. Using X-ray photoelectron spectroscopy, we quantitatively demonstrate that etching the GaAs at 200 W almost removed the GaAs oxide layer. To further study the surface passivation of GaAs, we deposited an AlN film by plasma-enhanced atomic layer deposition using trimethylaluminum and ammonia precursors at 250 °C. AlN passivation did not effectively smooth the GaAs surface, but did increase its photoluminescence intensity. This study shows that AlN coating by plasma-enhanced atomic layer deposition is a promising low-temperature method for GaAs surface passivation. [ABSTRACT FROM AUTHOR]

In this work, we perform a sulfur chemical passivation on GaAs substrate, which leads to a change in the photoluminescence (PL) owing to a reduction of surface states. By varying the reaction time of passivation, we can modify the chemical bonds of the GaAs surface and reduce the surface depletion region thickness, which strongly affects the emission efficiency of the GaAs band edge. Based on systematic PL measurements and energy band model with surface states, the sulfur passivation also enhances the number of free and bound excitons. Therefore, sulfur passivation is important to improve the performance of GaAs-based optoelectronics devices. [ABSTRACT FROM AUTHOR]

We investigated the suitability of aluminum nitride (AlN) for surface passivation and protection of gallium arsenide (GaAs), using a low-temperature passivation method. By varying the plasma power (100, 200 W) during etching, we found that 200 W produced better passivation. Using X-ray photoelectron spectroscopy, we quantitatively demonstrate that etching the GaAs at 200 W almost removed the GaAs oxide layer. To further study the surface passivation of GaAs, we deposited an AlN film by plasma-enhanced atomic layer deposition using trimethylaluminum and ammonia precursors at 250 °C. AlN passivation did not effectively smooth the GaAs surface, but did increase its photoluminescence intensity. This study shows that AlN coating by plasma-enhanced atomic layer deposition is a promising low-temperature method for GaAs surface passivation. [ABSTRACT FROM AUTHOR]

In this work, we perform a sulfur chemical passivation on GaAs substrate, which leads to a change in the photoluminescence (PL) owing to a reduction of surface states. By varying the reaction time of passivation, we can modify the chemical bonds of the GaAs surface and reduce the surface depletion region thickness, which strongly affects the emission efficiency of the GaAs band edge. Based on systematic PL measurements and energy band model with surface states, the sulfur passivation also enhances the number of free and bound excitons. Therefore, sulfur passivation is important to improve the performance of GaAs-based optoelectronics devices. [ABSTRACT FROM AUTHOR]

Molecular Beam Epitaxy (MBE) was used to grow GaSb thin films on GaSb substrates. We have obtained the optimized growth condition to improve films quality and the surface morphology of GaSb epilayer during growth. Two group samples were tested to study the influence of the growth rate and the V/III flux ratios on the crystal quality. It caused fewer defects when the growth rate of approximately was fixed 0.6 ML/s. And the surface morphology and performance was best for GaSb epilayer when the beam ratio was 5. The thin films were characterized by Atomic Force Microscopy (AFM) and high-resolution X-Ray Diffraction (XRD). The root means square roughness of the superlattice surface was only 0.335 nm. The full width at half maximum of the rocking curve was 39.6 arcsec and the emission wavelength of photoluminescence was 1.99 μm. [ABSTRACT FROM AUTHOR]

Without any catalysts-assisted, homobranched ZnO nano/microstructure had been synthesized via a simple low temperature water bath method. Such nano/microstructure which consists of shuttle-like nano/microrod backbone was surrounded by six radial oriented branches. The length of the shuttle-like ZnO nano/microrods is about 5–10 μm. The diameter of the single shuttle-like nano/microrods is 1–2.5 μm at the stem and 10–50 nm at the tip while the branches size from top to bottom is 10–50 nm to 0.5–1 μm. A strong ultraviolet emission and weak deep level emission reflect the high optical quality. In addition, a detailed discussion regarding the probable growth mechanism is presented in this work. [ABSTRACT FROM PUBLISHER]

Aiming to modification the surface optical properties, CdS/ZnO composites were synthesized by hydrothermal method. The ZnO/CdS heterostructures were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray energy dispersive spectroscopy (EDS), photoluminescence (PL) measurements at room temperature and the temperature-dependent photoluminescence treatment. In the room temperature PL spectra, the defect-related deep level emission can effectively suppress under optimal CdS deposition condition. With the increasing of CdS deposition time to 150 min, the donor bound exciton (D0X) peak showed a significantly red shift at low temperature (77K) PL spectrum. Through analysis the temperature-dependent photoluminescence spectra, we find that it was caused by acceptor bound exciton (A0X). Meanwhile, there appeared a donor-acceptor pair related emission at lower-energy side of the spectrum. The experiment demonstrated that the surface donor defects can effectively suppresse after CdS nanoparticles deposition on ZnO nanorods. [ABSTRACT FROM PUBLISHER]

As a kind of semiconductor material, the morphology of zinc oxide directly affects its physical properties. By adjusting the ratio of the reaction source and the rate of the incoming gas flow, we obtained one-dimensional nanowire and two-dimensional nanoflag-like functional gradient material (FGM) using chemical vapor deposition (CVD) method. Compared with the one-dimensional nanowires, the growth of the two-dimensional ZnO FGM not only c-oriented, but other directions are also appeared. Photoluminescence results show that the FGM has a higher visible/UV emission intensity ratio than the nanowires for several orders of magnitudes. Meanwhile, the growth mechanism of these nanostructures were discussed in details. [ABSTRACT FROM AUTHOR]

Mg-doped ZnO nanorods were prepared by electrochemical deposition method in aqueous solution. To test the sample, the results show that the sample presents a rod-like shape with hexagonal cross sections and typical morphology of wurtzite ZnO, and (002) diffraction peak of Mg-doped ZnO nanorods move to large-angle direction in XRD. The peak of Mg element has appeared in EDS. XPS shows that there is Mg-O binding in the sample. PL spectrums of the samples are observed at room temperature, the UV emission of Mg-doped ZnO presents blue shift compared with undoped ZnO, absorption spectrum shows that band gap of Mg-doped ZnO is larger. We can reach the conclusion that the Zn2+ions are successfully substituted by Mg2+ions in the ZnO lattice. In addition, photocatalysis property of Mg-doped ZnO nanorods is investigated. It is found that the degradation efficiency of methyl orange raise twice by Mg-doped ZnO nanorods in comparison to undoped ZnO nanorods. The result indicates that the photocatalysis activity of ZnO nanorods can enhance after Mg2+ions are doped into ZnO lattice. [ABSTRACT FROM AUTHOR]

Etching and sulfuring are equally important process during the surface sulfur passivation of gallium antimopnide (GaSb) In this work, we described the effects of etching by certain proportion of bromine methanol solution instead of hydrochloric acid solution (acidification), which could lead to a improvement of surface passivation homogeneity of GaSb. The photoluminescence (PL) spectra and the atomic force microscope (AFM) morphology on GaSb are also indicated a good surface morphology. [ABSTRACT FROM AUTHOR]