An efficient visible-light-sensitive heterostructure photoanode of CdS nanoparticles/ZnO shell/TiO2 nanotube (CdS/ZnO–TiNT) arrays were investigated for solar water splitting. Highly ordered arrays of TiNT were grown vertically on Ti foil by electrochemical anodization. Both aqueous solution routes were used in turn to coat a thin recombination barrier of ZnO shell and narrow band gap CdS nanoparticles to the surface of the TiNT arrays. As a result of strong absorption within solar spectrum and effective suppression of electron-hole pair recombination in CdS/ZnO–TiNT arrays, a significant improvement in solar-to-hydrogen conversion efficiency from 0.39% to 1.30% was obtained.

We have characterized the temperature dependence of band-edge transitions of three (Zn 0:38 Cd 0:62 ) 1Àx Be x Se II-VI films with different Be concentrations x by using contactless electroreflectance (CER) and piezoreflectance (PzR) in the temperature range of 15 to 450 K. By a careful comparison of the relative intensity of PzR and CER spectra, the identification of light-hole (lh) and heavy-hole (hh) character of the excitonic transitions of the samples has been accomplished. The temperature dependence analysis yields information on the parameters that describe the temperature variations of the energy (including thermal expansion effects) and broadening parameter of the band edge transitions of ZnCdBeSe. The study shows that Be incorporation can effectively reduce the rate of temperature variation of the energy gap.

The double-modulation reflectance technique has proven to be a powerful characterization tool of semiconductors applied in high-background–light-interference systems. In this article, we present a novel and inexpensive electronic-circuit design for implementing the double-modulation measurements using only one lock-in amplifier. The electronic design is fabricated in an accessory hardware of modulation spectroscopy which can easily select the double- or single-modulation mode via a manual switch. Detailed design diagrams of the electronic hardware are described. Measurements of some representative samples of semiconductors and actual device structures are carried out. Experimental results demonstrated the well-behaved performance of this design.

We report a detailed investigation of the temperature dependence of the band-edge excitonic transitions of three Zn1−x−yBexMgySe mixed crystals using contactless electroreflectance (CER) and photoreflectance (PR) in the temperature range of 15–400 K. The samples were grown by the modified high pressure Bridgman methods. The fundamental transition energy E0 and broadening parameters are determined via a lineshape function fit to the CER and PR spectra. The parameters that describe the temperature dependence of the band-edge excitonic transition energy and broadening parameters are evaluated and discussed.