Molecular beam epitaxy of GaSb on GaAs substrates with AlSb/GaSb compound buffer layers

GaSb films with AlSb/GaSb compound buffer layers were grown by molecular beam epitaxy on GaAs (001) substrates. The crystal quality and optical properties were studied by high resolution transition electron microscopy and low temperature photoluminescence spectra (PL), respectively. It was found that the AlSb/GaSb compound buffer layers can restrict the dislocations into GaSb epilayers. The intensity of PL spectra of GaSb layer becomes large with the increasing the periods of AlSb/GaSb superlattices, indicating that the optical quality of GaSb films is improved.

Carbon ceramic electrodes modified with sub-micron particles of new methylene blue (NMB) intercalated alpha-zirconium phosphate

New methylene blue-intercalated a-zirconium phosphate (NMBZrP) was synthesized in the presence of n-butylamine and characterized by powder XRD, FTIR, TEM and elemental analysis. Sub-micron particles of NMBZrP in deionized water were apt to deposit onto the surface of graphite powder to yield graphite powder-supported NMBZrP, which was subsequently dispersed into methyltrimethoxysilane-derived gels to fabricate surface-renewable, stable, rigid carbon ceramic electrodes containing new methylene blue. Cyclic voltammetric studies revealed that peak currents of the NMBZrP-modified electrode were surface-confined at low scan rates but diffusion-controlled. at high scan rates. In addition, NMBZrP immobilized in a carbon ceramic matrix presented a two-electron, three-proton redox process in acidic aqueous solution in the pH range from 0.52 to 3.95.