Femtosecond pulsed laser deposition of Ge quantum dot growth on Si(1 0 0)-(2 × 1)

Ge quantum dots were grown on Si(1 0 0)-(2 × 1) by femtosecond pulsed laser deposition at various substrate temperatures using a femtosecond Ti:sapphire laser. In situ reflection high-energy electron diffraction and ex situ atomic force microscopy were used to analyze the film structure and morphology. The morphology of germanium islands on silicon was studied at different coverages. The results show that femtosecond pulsed laser deposition reduces the minimum temperature for epitaxial growth of Ge quantum dots to ∼280 °C, which is 120 °C lower than previously observed in nanosecond pulsed laser deposition and more than 200 °C lower than that reported for molecular beam epitaxy and chemical vapor deposition.

► In this manuscript we report on our observation of germanium quantum dot formation on Si (100)-(2 × 1) by using femtosecond pulsed laser deposition (PLD). ► We have studied the shape transition of Ge quantum dots at different thicknesses and showed that using femtosecond pulses significantly reduces the epitaxial temperature compared to nanosecond PLD, MBE and CVD. ► We explain the mechanism responsible for the morphology change and epitaxial growth temperature.