Effects of adsorption kinetics on the low-temperature growth-rate activation energy in Si gas-source molecular beam epitaxy

Low-temperature growth-rate activation energy E_g for the growth of Si hydrides and the hydrogen desorption energy E_d from Si surfaces are shown to differ from each other (E_g<E_d) as opposed to E_g = E_d, which has been frequently postulated. A comparative growth study of silane and disilane gas-source molecular beam epitaxy clarifies that this difference arises from non-negligible contributions from the adsorption kinetics in the formation of E_g. Based on this knowledge, a method for determining the true E_d values is presented, and its validity is demonstrated by a successful reduction to an identical E_d value (2.0 eV), which was determined from much less, and mutually different E_g values of silane and disilane growth.