Role of Vacancy Annihilation in Electrical Activation of P Implanted in Ge

Due to the scaling limit faced by Si CMOS technology, much interest is being given on Ge. However, development of the Ge device technology requires more research into the fabrication processes. In this study, we have investigated the doping characteristics of P in Ge as a function of the dopant dose and substrate orientation. It is found that recovery characteristics of damaged layers depends on crystal orientation of the Ge substrates for samples having completely amorphized surface-layers produced by high-dose (1x10^<15> cm^<-2>) implantation. This is due to orientation-dependent regrowth velocity of Ge. On the other hand, no orientation dependence is observed for samples implanted with low dose (5x10^<13>-1x10^<14> cm^<-2>), whose surface layers are partially amorphized. For high-dose samples, the complete carrier-activation coincides with the damage-recovery at 350-400℃. However, higher temperature annealing (500-550℃) is necessary for carrier activation in low-dose samples, though crystallinity recovers at 250-300℃. The temperature-dependence of the carrier-activation ratio suggests that carrier-activation in low-dose samples is mediated by vacancy-migration.