Optical Properties of Silicon Nanoparticles in Silica Gel Monoliths
- PDF / 146,206 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 55 Downloads / 238 Views
F3.54.1
OPTICAL PROPERTIES OF SILICON NANOPARTICLES IN SILICA GEL MONOLITHS Y. Posada, L. San Miguel, L. F. Fonseca, O. Resto, S. Z. Weisz, Department of Physics, University of Puerto Rico, Rio Piedras, 00931 PR
ABSTRACT We have synthesized highly photoluminescent monoliths by incorporating nanocrystalline Silicon (nc-Si) from Porous Silicon (PSi) into a Sol Gel Silica matrix. The optically transparent samples are the result of mixing an acid catalyzed solution of Sol-Gel and nc-Si that forms a solution of Si-nanoclusters (Si-n) that eventually after condensation for three days produces the final luminescent material. Photoluminescence (PL) basic studies show a very high orange emission band with a maximum peak that ranges between 600 nm and 750 nm. The PL emission intensity was increased up to ten times the luminescence of the native nano material PSi, the mechanical and thermal stability properties were also greatly improved. The PL corresponds to different concentrations or preparations of Sol-Gel with Si-n (Sol-Si) with a broad size distribution that produces orange and blue emissions, and for this reason we take as our future work to tailor samples with very high Si-n densities for semiconducting and photonic applications. INTRODUCTION Silicon based microelectronics are the most extensively products used for industrial applications, therefore research in this field should give rise to new and more versatile materials to fit the necessity of more digitalized smaller devices. One of the most studied Si-based systems is PSi [1], a system that offers a great variety of photonic applications because its PL and optical properties can be used to fabricate photosensors, photomolecular imprinting, applications in life sciences, and many other technological applications. We have integrated successfully PSi as the main nano material used on the fabrication of Sol-Si monoliths. The Silica matrix in which the Silicon crystallites are imbedded is produce by standard methods of Sol-Gel Silica Glass fabrication. In this new environment the nc-Si tends to form Si-n that are surrounded by the Silica as a shell protector giving the native material PSi ultra mechanical strength, very high luminescence, thermal stability up to 250 C and power light emission tunnability and visible and ultraviolet filtering properties. The PL of Sol-Si is very stable and its quality does not change with the natural aging process suffered by the Sol-Gel Silica, therefore no special additional chemical passivation [2] of the nc-Si surfaces have been used to maintain the PL for long periods of time. In diluted samples a blue shift of the PL peak is observed when compared to the PSi PL peak. A basic optical characterization of Sol-Si is presented here along with a discussion on its structure formation and the relevant role played by the concentration of Si-n o the PL and other optical properties of this material.
F3.54.2
SAMPLE PREPARATION The PSi is made by the electroetching of Silicon p-type wafers in a 25% HF solution as electrolyte with a curr
Data Loading...
