Kinetics of dopant incorporation using a low-energy antimony ion beam during growth of Si(100) films by molecular-beam epitaxy

Abstract

n-type Si(100) films have been grown by molecular-beam epitaxy utilizing low-energy Sb ion-beam doping. The kinetics of dopant incorporation were investigated as a function of acceleration potential &=50–400 V), deposition temperature ($T_s$=550–1050 °C), and Si growth rate ($R_{\mathrm{Si}=0.05\mathrm{}}$–0.8 nm ${\mathrm{s}}^{\mathrm{-}1}$). The & using accelerated-ion doping was up to 5 orders of magnitude higher than was & was &≥300 V at $T_s$≤850 °C. At lower acceleration potentials, & was temperature and deposition-rate dependent. &=50 V and & was still more than 1 order of magnitude higher than for thermal doping. Moreover, surface-segregation-induced profile broadening ${\Delta }_{\mathrm{Sb}}$, which for thermal-beam doping was ≥80 nm per concentration decade for $T_s$≤650 °C, was less than the depth resolution of the measurement, i.e., ${\Delta }_{\mathrm{Sb}\mathrm{\le }12}$ nm per concentration decade. The experimental incorporation results, &,$T_s$,$R_{\mathrm{Si}}$), were found to be well described using a multisite model (including surface, bulk, and three intermediate sites) in which dopant surface segregation, incorporation, and bulk diffusion are accounted for by solving simultaneous transition-rate equations.