Photoluminescence investigation on growth mode changeover of Ge on Si(100)

Growth mode changeover during gas source molecular beam epitaxy of Ge on Si(100) is explored by photoluminescence (PL) spectroscopy with a subatomic layer resolution. By observing confinement effect and development of island-related emissions with increasing Ge coverage in Si/pure-Ge/Si quantum wells, the onset of the island formation is determined to be 3.7 monolayers (ML). Furthermore, the equilibrium critical thickness for island formation is found to be lower, i.e. 3.0 ML, by adopting growth interruption after the Ge growth. Intense quantum-confined PL is clearly observed at room temperature from the islanded Ge of quantum dot character, demonstrating the potential of the Ge islands as efficient light emitters.