Recrystallization of implanted amorphous silicon layers. I. Electrical properties of silicon implanted with BF+2 or Si++B+

Abstract

Electrical properties of recrystallized amorphous silicon layers, formed by BF+2 implants or Si++B+ implants, have been studied by differential resistivity and Hall-effect measurements. Electrical carrier distribution profiles show that boron atoms inside the amorphized Si layers can be fully activated during recrystallization at 550 °C. The mobility is also recovered. However, the tail of the B distribution, located inside a damaged region near the original amorphous-crystalline interface, remains inactive. This inactive tail has been observed for all samples implanted with BF+2. Only in a thicker amorphous layer, formed for example by Si+ predamage implants, can the entire B profile be activated. The etch rate of amorphous silicon in HF and the effect of fluorine on the recrystallization rate are also reported.