Melting behavior of as-deposited and recrystallized indium nanocrystals

Melting behavior of as-deposited and recrystallized indium nanocrystals is studied using reflection high-energy electron diffraction in its transmission mode. Indium films with mean thickness ranging from 1.5 to 10 monolayers (ML) deposited on highly oriented graphite at different substrate temperatures are studied. Atomic force microscopy is used to study the crystal size and morphology of the as-deposited and recrystallized nanocrystals. As-deposited films are found to form shallow nanocrystals with a flat top surface of different shapes, while the recrystallized nanocrystals are formed in the more rounded polyhedral shape. The change in the diffraction pattern intensity with temperature is used to probe the melting of the nanocrystals. The melting point is found to be lower than that of the bulk for both types of films and extends over a temperature range due to nanocrystal size distribution. The as-deposited films show an end melting point nearly equal to that of the recrystallized films except for the 1.5-ML film which shows an end melting point ∼10 K lower than the recrystallized film. The deposition temperature is found to have a significant effect on the end melting point of as-deposited nanocrystals, while having a negligible effect on the end melting point of recrystallized nanocrystals.