The morphological evolution and the effect of growth temperature on size, orientation and composition of molecular beam epitaxy grown Ge-Si islands on Si(5 5 12) surfaces have been investigated in the temperature range from room temperature (RT) to 800∘C. Two modes of substrate heating i.e. radiative heating (RH) and direct current heating (DH) have been used. The post-growth characterization was carried out ex situ by scanning electron microscopy (SEM), cross-sectional transmission electron microscopy (X-TEM) and Rutherford backscattering spectrometry (RBS). In the RH case, we found spherical island structures at 600∘C with a bimodal distribution and upon increasing temperature, the structures got faceted at 700∘C. At 800∘C thick (∼ 122nm) dome like structures are formed bounded by facets. While in the case of DC heating, after the optimum critical temperature 600∘C, well aligned trapezoidal Si1−xGex structures with a graded composition starts forming along the step edges. Interestingly, these aligned structures have been found only around 600∘C, neither at low temperature nor at higher temperatures.
@article{arxiv.1205.6039,
title = {Shape evolution of MBE grown Si$_{1-x}$Ge$_{x}$ structures on high index Si(5 5 12) surfaces: A temperature dependent study},
author = {J. K. Dash and A. Rath and R. R. Juluri and P. V. Satyam},
journal= {arXiv preprint arXiv:1205.6039},
year = {2012}
}