Low-temperature Si(001) epitaxy using low-energy (〈E 〉≂18 eV) Si atoms

The use of energetic (average energy ≂18 eV), rather than thermal (≂0.2 eV), Si beams during deposition at R=1 Å s−1 was found to increase the Si(001) epitaxial thickness te (100 Å–1.2 μm) by up to an order of magnitude over the growth temperature range Ts=80–300 °C. The overall increase in te is attributed primarily to a more effective filling of interisland trenches which form during growth in the low adatom mobility two-dimensional multilayer mode and provide preferential sites for the nucleation of the terminal amorphous phase. In addition, the behavior of te(Ts) at constant R and te(R) at constant Ts is quite different than that reported for films grown by molecular-beam epitaxy. A decrease in the slope of ln(te) versus −1/Ts at Ts<225 °C indicates an additional increase in the epitaxial thickness at very low growth temperatures while at constant Ts, 150 °C, te increases with decreasing R, reaches a maximum, and then decreases. These latter effects are explained in terms of changes in average island sizes giving rise to corresponding changes in interlayer mass transport.