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We have found a new electron trap state in Si-doped AlxGa1−xAs by deep level transient spectroscopy and constant temperature capacitance transient measurements under strong light illumination. This new trap is shallower than the DX center associated with Si impurity in that its emission and capture activation energies are equal to 0.20±0.05 and 0.17±0.05 eV, respectively. Its maximum concentration is comparable to the concentration of the DX center. Possible origins of this new trap and its relationship to the DX center are discussed.

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Abstract:The layered perovskite, K 2 La 2 Ti 3 O 10 was prepared by sol-gel method. Ion-exchange of Cu 2+ was prepared to improve the photocatalytic activity of K 2 La 2 Ti 3 O 10 for chlorobenzene degradation under simulated solar light irradiation. The original K 2 La 2 Ti 3 O 10 and Cu 2+ /K 2 La 2 Ti 3 O 10 were characterized by power X-ray diffraction, UV-visible diffuse reflectance spectroscopy, and specific surface area measurement. The XRD analysis shows that Cu 2+ ions is incorporated in place of K + ions and the grain growth is inhibited by ion-exchange. With the rise of calcination temperature, more interlayer Cu 2+ was converted into new crystal phase CuO. The degradation ratio reaches 51.1% on Cu 2+ /K 2 La 2 Ti 3 O 10 calcined at 500 • C in air, which is higher 16.9% than the original K 2 La 2 Ti 3 O 10 . It should be ascribed to the narrow interlayer distance, the formation of CuO, smaller grain size, and the high visible light absorption on the surface of Cu 2+ /K 2 La 2 Ti 3 O 10 calcined at 500 • C. It is found that the exposure of CO 2 could promote the photocatalytic activity of Cu 2+ /K 2 La 2 Ti 3 O 10 . It also suggests that CO 2 is involved in the reduction to form benzaldehyde during decomposition of chlorobenzene.