Limiting thickness hₑₚᵢ for epitaxial growth and room-temperature Si growth on Si(100)

Si molecular-beam epitaxy (MBE) on smooth Si(100) surfaces is shown to occur at room temperature. We demonstrate for the first time that Si deposition becomes amorphous after growth of a limiting epitaxial thickness (hₑₚᵢ). hₑₚᵢ is {}10--30 {} at room temperature and increases rapidly at higher temperatures with a rate-dependent activation energy in the range 0.4--1.5 eV. The effect is tentatively linked to surface roughening during growth at low temperatures, and is probably general in MBE, also occurring for Si/Si(111), Ge/Si(100, and GaAs/GaAs(100).