In situ optical second-harmonic-generation monitoring of disilane adsorption and hydrogen desorption during epitaxial growth on Si(001)

The kinetics of disilane adsorption and hydrogen desorption during low-temperature, ultrahigh vacuum chemical vapor deposition on Si(001) is investigated in situ in real time by monitoring the instantaneous hydrogen coverage using optical second-harmonic generation. A simple two-site adsorption model and first-order desorption are used to establish a reactive sticking coefficient and to predict the Si(001) epitaxial growth rate. The reactive sticking coefficient is temperature independent between 740 and 920 K and equal to 0.04±0.01. Predicted growth rates are in agreement with published growth rates obtained from gas-source molecular-beam epitaxy of Si(001).