OPTOELECTRONIC APPLICATIONS OF POROUS POLYCRYSTALLINE SILICON

We report visible light emission from porous structures formed in bulk and thin-film polycrystalline silicon materials by anodic etching in an HF:ethanol solution. Our results indicate photoluminescence (PL) pe aks at wavelengths between 650 and 655 nm and with intensities compara ble to those typically obtained from porous samples of single-crystal silicon. The analyses of the surface morphology of porous polycrystall ine silicon (PPSI) layers suggest that the etch rate could be preferen tially greater at the grain boundaries. We have illuminated PPSI films formed on quartz substrates from both the front and rear of the sampl es and have measured PL emission from the same corresponding sides. Lu minescent polycrystalline silicon films offer the possibility of integ rating a novel Si-based flat-panel display along with the recently dev eloped thin-film transistor (TFT) driver circuitry on a glass substrat e. In addition, nanostruetures originating from polycrystalline silico n substrates may enable low-cost fabrication of highly efficient photo voltaic cells.