Nanometer-scale composition measurements of Ge/Si(100) islands

Quantitative, nanometer-scale spatial resolution electron energy-loss spectroscopy (EELS) was used to map the composition of coherent islands grown by molecular-beam epitaxy of pure Ge onto Si(100). The Ge concentration X-Ge decreased, and the Ge/Si interface became more diffuse as the growth temperature increased from 400 to 700 degreesC. Integrated island volumes measured by atomic force microscopy (AFM) increased linearly with Ge coverage theta(Ge), with slopes greater than 1. This result confirmed that island growth is faster than the Ge deposition rate due to Si interdiffusion. The linearity of the island volume versus theta(Ge) curves implied that X-Ge was independent of island size. X-Ge measured by EELS and AFM agree well with each other and correctly predicted the minimum dome size observed at each growth temperature. (C) 2003 American Institute of Physics.