Temperature-dependent vacancy formation during the growth of Cu on Cu(001)

Abstract

X-ray diffraction measurements show that a large number of vacancies are incorporated in thin Cu films grown on Cu(001) at low temperatures. At any given deposition temperature between 110 and 160 K, the vacancy concentration cv, obtained from reflectivity data, does not change with the coverage Θ, for 2.5ML<~Θ<~20ML. However, cv is temperature dependent: for 15-ML-thick films, grown at different temperatures, it monotonically decreases with increasing T from cv≈2% at 110 K to zero at T=160K. A different “cv vs T” dependence is observed for films grown at 110 K and then annealed at progressively higher temperatures. Here cv≈2% persists over a broad temperature interval (between 110 and 200 K) and cv exhibits a slower decrease upon heating, reaching zero at 300 K.