Growth of Si Clathrate Films with Various Annealing Conditions

Abstract

Si clathrate thin films were fabricated by using Si(111) substrates, Na lumps and NaH powder at various conditions in two steps annealing process. The duration of the first annealing to prepare precursor films affected the thickness and the surface morphology of the final products, i.e., Si clathrate films. The annealing duration of 18 h led to Si clathrate films of 1-2 m in thickness. Attempts to control the rate of reduction of Na from the precursor films were carried out in the second step annealing under vacuum. The obtained results suggested that the rate of Na reduction affects the structure type (type I or II) of clathrate.