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 \ifmmode^\circ\else\textdegree\fi{}C), and Si growth rate (${R}_{\mathrm{Si}=0.05}$--0.8 nm ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$). The using accelerated-ion doping was up to 5 orders of magnitude higher than was was \ensuremath{\ge}300 V at ${T}_{s}$\ensuremath{\le}850 \ifmmode^\circ\else\textdegree\fi{}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 ${\ensuremath{\Delta}}_{\mathrm{Sb}}$, which for thermal-beam doping was \ensuremath{\ge}80 nm per concentration decade for ${T}_{s}$\ensuremath{\le}650 \ifmmode^\circ\else\textdegree\fi{}C, was less than the depth resolution of the measurement, i.e., ${\ensuremath{\Delta}}_{\mathrm{Sb}\mathrm{\ensuremath{\le}}12}$ 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.