ENHANCEMENT AND SUPPRESSION OF THE FORMATION OF POROUS SILICON

We present the results of an investigation of various means to enhance or suppress the formation of porous silicon. The first method involves a lithographic process using silicon nitride to produce sub-0.5 μm light emitting porous silicon (LEPSi) lines adjacent to fully protected silicon regions. The second method consists of amorphizing regions of the wafer prior to anodization with high energy/high dose ion implantation, followed by anodization and annealing. In this method, LEPSi is produced in the unimplanted regions only. Using focused ion-beam implantation approx. 100 nm patterns have been obtained. The third method utilizes low energy/low dose bombardment (ion milling/reactive ion etching) with argon ions prior to anodization. Under appropriate bombardment conditions, we have observed a strong enhancement of the formation rate of LEPSi, possibly due to the generation of a large number of defects on the wafer surface. Our results demonstrate that porous silicon light emitting diodes (LEDS) and silicon electronic devices can coexist in close proximity (within 1 μm or less) on the same chip.