Effects of high B-doping an Si(001) dangling bond densities, H desorption and film growth kinetics during gas-source molecular beam epitaxy

Si(001) layers doped with B concentrations C-B ranging from 5 x 10(16) to 2 x 10(21) cm(-3) were grown on Si(001)-(2 x 1) substrates by gas-source molecular beam epitaxy using Si2H6 and B2H6. B was incorporated into substitutional electrically active sites at concentrations up to 2.5 x 10(20) cm(-3). With increasing incident flux ratios J(B2H6)IJ(Si2H6)greater than or equal to 0.01 (corresponding to C-B=2 x 10(19) cm(-3)), film growth rates decreased at T-s greater than or equal to 600 degrees C, but increased al T-s less than or equal to 550 degrees C. Deuterium temperature-programmed desorption measurements as a function of increasing C-B show strong B surface segregation, decreased steady-state H coverages theta(H), and lower dangling bond densities. The Si:B growth kinetics are well described by a model showing that at low temperatures, where steady-state theta(H) values are high, increased H desorption rates from B-backbonded Si adatoms dominate, leading to an enhancement in R-Si, whereas at higher temperatures R-Si decreases due to the decreased adsorption-site density. (C) 1997 Elsevier Science B.V.