The broadband absorption of metal-oxide-semiconductor SiGe/ Si quantum dot infrared photodetectors is demonstrated using boron ␦ doping in the Si spacer. The peak at 3.7-6 m results from the intersubband transition in the SiGe quantum dot layers. The other peak at 6 -16 m mainly comes from the intraband transition in the boron ␦-doping wells in the Si spacers. Since the atmospheric transmission windows are located at 3-5.3 and 7.5-14 m, broadband detection is feasible using this device. The ␦ doping in SiGe quantum dots and Si 0.9 Ge 0.1 quantum wells is also investigated to identify the origin of the absorption.

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In this paper, Cu(x)O photocatalyst on plasmonic nanoporous Au film is proposed to enhancing the H(2) evolution rate of pure water splitting. The nanoporous Au film can simultaneously provide surface-enhanced absorption and built-in potential. The reflection spectrum shows that the surface plasmon (SP) assisted absorption wavelength of the Cu(x)O on the nanoporous Au film can be modified by changing the annealing temperature. It is found that the enhancement of the H(2) evolution rate highly depends on the SP-assisted absorption. As the annealing temperature is 220 ° C, the H(2) evolution rate is 58 μmol hr(-1) under the condition that the device area is 0.25 cm(2).

A template- and surfactant-free process, thermally assisted photoreduction, is developed to prepare vertically grown ultra-long Pt nanowires (NWs) (about 30-40 nm in diameter, 5-6 μm in length, and up to 80 NWs/100 μm2 in the wire density) on TiO2 coated substrates, including Si wafers and carbon fibers, with the assistance of the photocatalytic ability and semiconductor characteristics of TiO2. A remarkable aspect ratio of up to 200 can be achieved. TEM analytical results suggest that the Pt NWs are single-crystalline with a preferred 〈111〉 growth direction. The precursor adopted and the heat treatment conditions are crucial for the yield of NWs. The photoelectrons supplied by TiO2 gives rise to the formation of nano-sized Pt nuclei from salt melt or solution. The subsequent growth of NWs is supported by the thermal electrons which also generated from TiO2 during the post thermal treatment. The interactions between the ions and the electrons in the Pt/TiO2 junction are discussed in this study.