5 keV to 2 MeV lithium implantation and diffusion in amorphous silicon

Abstract

Abstract Low dose implanted lithium depth profiles in preamorphized silicon have been measured in the energy range of 5 keV to 2 MeV by means of three different nuclear reaction techniques and SIMS measurements, and they are compared to theory. Though the agreement is good for the mean projected range, we find systematic deviations for the range straggling. Further, the shapes of lithium depth profiles are studied as a function of the preamorphization dose. Also, the diffusion of li in amorphous Si was measured between – 18 and + 350°C. It is described by D = D 0·exp(-EA/kT), the value of D 0 and EA ranging from those for purely interstitial diffusion (D 0 = 2 · 10−(4±0.5) cm2 s−1 and EA = 0.74 ± 0.5 eV) up to higher ones, which describe trap controlled diffusion (D 0 = 3 × 10+(3±1) cm2 s−1 and E = 1.74 ± 0.1 eV). A gradual transition between those extremes with diffusion time is observed.