Growth of germanium quantum dots on different dielectric substrates by chemical-vapor deposition

The growth of Ge quantum dots on various nitrided oxides has been achieved by ultra-high-vacuum chemical-vapor deposition with GeH4 gas at temperature s between 550 and 650 degreesC. The characteristics of the Ge dots were inv estigated using atomic-force microscopy, Auger electron spectroscopy, and x -ray photoelectron spectroscopy in order to find the mechanism of the Ge do t formation. On N2O-annealed nitrided oxide films, we obtained Ge dots with height and diameters of 3.2 and I I nm, respectively. No Ge dots were form ed on surfaces of other dielectric substrates at 550 degreesC. From our exp erimental results, we suggest that the surface of N2O-annealed nitrided oxi de contains a large amount of defects such as dangling bonds, which act as Ge nucleation sites. This is further confirmed by studying the growth kinet ics and the influence of in situ annealing of the samples. (C) 2001 America n Vacuum Society.