Abstract
The growth of titanium suicide clusters has been observed for sub-monolayer Ti deposited on Si(111)-7 × 7. Irregular shape tetragonal Ti 5 Si 4 islands were observed to grow at 600°C. On the other hand, the elongated orthorhombic-Ti 5 Si 4 (O-Ti 5 Si 4 ) clusters form at 700°C. The clusters underwent a rapid increase in length and slight reduction in width as the cluster area exceeds a critical size (∼15 nm 2 ). The elongated clusters are oriented along three equivalent Si(2-20) directions of the Si(111) surface with O-Ti 5 Si 4 (025)//Si(2-20). The shape change is in agreement with theoretical prediction based on the strain relief mechanism.