Dopant Induced Stabilization of Silicon Cluster at Finite Temperature

摘要

With the advances in miniaturization, understanding and controllingproperties of significant technological systems like silicon in nano regimeassumes considerable importance. It turns out that small silicon clusters inthe size range of 15-20 atoms are unstable upon heating and in fact fragment inthe temperature range of 1200 K to 1500 K. In the present work we demonstratethat it is possible to stabilize such clusters by introducing appropriatedopant (in this case Ti). Specifically, by using the first principle densityfunctional simulations we show that Ti doped Si$_{16}$, having the Frank-Kaspergeometry, remains stable till 2200 K and fragments only above 2600 K. Theobserved melting transition is a two step process. The first step is initiatedby the surface melting around 600 K. The second step is the destruction of thecage which occurs around 2250 K giving rise to a peak in the heat capacitycurve.