| The continuous evolution of silicon microelectronics has produced significant gains in electronic information processing. However, greater improvements in performance are expected by utilizing optoelectronic techniques. But these techniques have been severely limited in silicon-based optoelectronics due to the lack of an efficient silicon light emitter. The recent observation of efficient light emission from porous silicon offer a promising opportunity to develop a suitable silicon light source that is compatible with silicon microelectronics. This dissertation examined the porous silicon emission mechanism via photoluminescence, and by a novel device structure for porous silicon emitters.; The investigation first examined the correlation between porous silicon formation conditions (and subsequent morphology) with the resulting photoluminescence properties. The quantum confinement theory for porous silicon light emission contends that the morphology changes induced by the different formation conditions determine the optical properties of porous silicon. The photoluminescence spectral shifts measured in this study, in conjunction with TEM analysis and published morphological data, lend support to this theory. However, the photoluminescence spectral broadening was attributed to electronic wavefunction coupling between adjacent silicon nanocrystals.; An novel device structure was also investigated in an effort to improve current injection into the porous silicon layer. The selective etching properties of porous silicon were used to create a p-i-n structure with crystalline silicon contacts to the porous silicon layer. The resulting device was found to have unique characteristics, with a negative differential resistance region and current-induced emission that spanned from 400 nm to 5500 nm. The negative differential resistance was correlated to resistive heating effects in the device. A numerical analysis of thermal emission spectra from silicon films, in addition to direct comparisons with resistively-heated silicon filaments, demonstrated a close correspondence to the porous silicon emitters' infrared spectra. The 6% external quantum efficiency, and over 1 mW of optical power emitted in the 400--2500 nm range, were the highest reported for any porous silicon device. A porous silicon interconnect process was also developed to integrate these devices with microelectronics technology. The emission produced by these emitters may be suitable for infrared spectroscopy and sensor applications. |
