Shape stability of TiSi2 islands on Si (111)

The evolution of the shape and size of TiSi2 islands on Si (111) surfaces is explored with real time ultraviolet photoelectron emission microscopy. During continuous deposition of Ti at elevated temperatures, individual islands in a dilute surface distribution grow larger without island-island interactions. As they increase in size, symmetric islands transform into elongated shaped islands with high length-to-width aspect ratios. An extremely elongated island shows a ratio of 85:1 and is similar to17 mum long and similar to0.2 mum wide. The individual elongated islands have different widths regardless of their length. The width of the growing islands is determined at the initial transition stage and remains essentially constant with increasing length. We propose that the various widths of the elongated islands are determined by the degree of strain relaxation, possibly through the nucleation of dislocations at the island interface. In addition, it is found that the elongated islands display a prism-like shape or a truncated prism-like shape. We propose that the shape evolution of the elongated islands is related to both strain relaxation and growth kinetics. (C) 2004 American Institute of Physics.