370 °C clean for Si molecular beam epitaxy using a HF dip

We describe a new low‐temperature clean for Si molecular beam epitaxy. Growth is carried out on Si wafers subjected to an ≊10–60 s clean in a buffered HF solution prior to insertion in the growth chamber. We demonstrate low defect densities (<105 cm−2) at 380 °C without either the conventional high‐temperature cleaning step to desorb a chemical oxide or the use of a glovebox for chemical cleaning and transfer to the vacuum chamber. Wafers are given an ≊200 °C prebake in situ to remove hydrocarbons, and then raised to the growth temperature prior to deposition. For (100) substrates the transition from amorphous deposition to crystalline growth occurs at ≊370 °C, below the temperature at which hydrogen should desorb. On (111) the minimum temperature for epitaxy is ≊500 °C, as expected. We attribute this difference to the large number of undercoordinated Si atoms present on (100), which allows growth to take place even on the hydrogen‐terminated surface. Secondary‐ion mass spectrometry suggests that contamin...