SiO₂/PbTe Quantum Dots multilayers for the 1.3-1.5 μm region

Multilayers of PbTe quantum dots embedded in SiO₂ were fabricated and characterized by means of Fourirer transform infrared and x-ray spectrometry and transmission electron microscopy. The quantum dots were grown by laser ablation of a PbTe target using the second harmonic of a Q-Switched Quantel Nd:YAG laser under high purity argon atmosphere. The glass matrix was fabricated by Plasma Enhanced Chemical Vapor Deposition using tetramethoxysilane as precursor. The reason for choosing PbTe was the absorption bands this material exhibits in the region of interest for optical communications 1.3-1.5μm making this material an excellent candidate for development of optical devices. For the glass matrix, it was studied the influence of growing parameters like RF power, distance between the RF electrodes and the total pressure in the properties of the SiO₂ films. The parameters for the PbTe ablation were assumed from a previous work. FTIR and refractive index measurements were used to estimate the best growth parameters for the dielectric host. TMOS partial pressure proved to be an important parameter to diminish the nanoparticle coalescence during the multilayer fabrication. Multilayer X-ray diffraction patterns were used to estimate the nanoparticles diameter. Morphological properties of the nanostructured material were studied using transmission electron microscopy.