Abstract
We have found that Pt thin films deposited on chemical-vapor-deposited diamond significantly changed in form at temperatures of ≈ 900°C, which are well below the melting point of Pt, 1776°C. Such structural changes occurred after diamond overgrowth, hydrogen plasma irradiation, or thermal annealing around diamond growth temperatures in vacuum or hydrogen ambient. For Pt films thinner than 100 nm, roughly spherical Pt particles formed were found to be rather uniform in size. In this case, the particle size is controllable by changing Pt thicknesses before the morphology changes. It is suggested that the possible mechanism of the observed low-temperature morphology changes is related to an interaction between Pt and hydrogen around ≈ 900°C.
