DIFFUSION, EVAPORATION AND RECRYSTALLIZATION IN HG-IMPLANTED AMORPHOUS SI

Silicon wafers were amorphized by 2 x 10(15) Ar+/cm(-1) and 3 x 10(17) Ar+/cm(-2) (abbreviated by a-Si and a-Si(Ar), respectively) and subsequently implanted with 400 keV Hg+ to a dose of 4 x 10(15) ions/cm(-2). The diffusion and evaporation of the implanted Hg and recrystallization of the Hg-implanted amorphous Si have been studied over the temperature range of 700-1000 degrees C by MeV He ion Rutherford backscattering/channeling technique. It is found that at 700 degrees C, thermal diffusion dominates and there is no loss of implanted Hg in a-Si. The diffusion coefficient obtained is 7.8 x 10-(15) cm(2) s(-1). Above 800 degrees C, the evaporation is a dominant mechanism. At 1000 degrees C, the implanted Hg disappears. Recrystallization phenomena is also observed. But for a-Si(Ar) at 700 degrees C, 87% of the implanted Hg is lost and at 800 degrees C the Hg disappears totally. The remaining Ar segregates towards the surface and amorphous-crystalline interfaces.