Cellular breakdown and carrier lifetimes in gold-hyperdoped silicon

Abstract

Ion implantation of transition metals into Si, followed by pulsed laser melting and rapid solidification, shows promise for making Si devices with sub-band gap optoelectronic response. We study Si implanted with Au at doses ranging from 1015–1016 at cm−2, with all but the lowest dose exhibiting interface breakdown during solidification, resulting in heavily defected layers. Terahertz photocarrier lifetime measurements confirm that layers with breakdown show recombination lifetimes of about 100 ps, compared to 800 ps for a layer with no breakdown. Device measurements, however, show more photoresponse at 1550 nm in a layer with breakdown than in a layer without. The results suggest that avoiding breakdown may be desirable but might not necessarily be imperative for making a useful device.