Spatially Confined Chemistry:  Fabrication of Ge Quantum Dot Arrays

We report a technique for investigating nucleation and growth confined to nanometer scale surfaces. Lithographic and etching processes were used to create arrays of 100 and 150 nm holes through a thin SiO2 layer onto Si(100). Ge dots were nucleated and grown to a few nanometers in diameter within the patterned wells. Transmission electron and atomic force microscopic analyses revealed the presence of 0−1 Ge quantum dots in each of the 100 nm wells and 2−4 dots in the 150 nm wells. For the latter case, size−distance correlations indicated the effective radius of the diffusion field around a growing Ge particle was much larger than for growth on an infinite surface.