Nonthermal laser-induced formation of crystalline Ge quantum dots on Si(100)

The effects of laser-induced electronic excitations on the self-assembly of Ge quantum dots on Si ( 100 ) - ( 2 × 1 ) grown by pulsed laser deposition are studied. Electronic excitations due to laser irradiation of the Si substrate and the Ge film during growth are shown to decrease the roughness of films grown at a substrate temperature of ∼ 120 ° C . At this temperature, the grown films are nonepitaxial. Electronic excitation results in the formation of an epitaxial wetting layer and crystalline Ge quantum dots at ∼ 260 ° C , a temperature at which no crystalline quantum dots form without excitation under the same deposition conditions.