A study was made of doping profiles, activation levels, and defect annealing of P introduced in Ge by ion implantation at different doses and energy, and annealed under various conditions by rapid thermal annealing. Common to all implant energies, ion-implanted P in Ge exhibited a so-called box-profile at high implant doses, when a sufficiently high thermal budget was applied—similarly to the concentration-dependent diffusion of P introduced in Ge from a high-concentration solid source. Upon proper annealing conditions, the active P concentration was limited to (5–6) x 1019at/cm3, implying a 50% activation level of the total retained atoms for high-dose implants and 100% for the low-dose implants. A low thermal budget was sufficient to regrow fully the amorphous layer formed by high-dose P implantations, without evidence of residual defects in the regrown Ge layer and at the end of range of the P implant.

P Implantation Doping of Ge - Diffusion, Activation and Recrystallization. A.Satta, T.Janssens, T.Clarysse, E.Simoen, M.Meuris, A.Benedetti, I.Hoflijk, B.De Jaeger, C.Demeurisse, W.Vandervorst: Journal of Vacuum Science & Technology B, 2006, 24[1], 494-8

Figure 10

Diffusivity of P in Si

(Open squares: interstitial mechanism D = 2.3 x 10-1exp[-2.6(eV)/kT], open circles: vacancy mechanism D = 7.6 x 104exp[-5.2(eV)/kT], filled circles: interstitial mechanism D = 4.9 x 10-6exp[-2.1(eV)/kT])