Using molecular-dynamics simulation techniques, we have investigated the role that point defects and interstitial-vacancy complexes have on the silicon amorphization process. We have observed that accumulation of interstitial-vacancy complexes in concentrations of 25% and above lead to homogeneous amorphization. However, we have determined the basic properties of the interstitial-vacancy complex, and showed that it is not as stable at room temperature as previously reported by other authors. From our simulations we have identified more stable defect structures, consisting of the combination of the complex and Si self-interstitials. These defects form when there is an excess of interstitials or by incomplete interstitial-vacancy recombination in a highly damaged lattice. Unlike the interstitial-vacancy complex, these defects could survive long enough at room temperature to act as embryos for the formation of extended amorphous zones and/or point defect clusters.