On the epitaxy of twin-free cubic (111) praseodymium sesquioxide films on Si(111)

Abstract

Twin-free epitaxial cubic (111) praseodymium sesquioxide films were prepared on Si(111) by hexagonal-to-cubic phase transition. Synchrotron radiation grazing incidence x-ray diffraction and transmission electron microscopy were applied to characterize the phase transition and the film structure. As-deposited films grow single crystalline in the (0001)-oriented hexagonal high-temperature phase of praseodymium sesquioxide. In situ x-ray diffraction studies deduce an activation energy of 2.2eV for the hexagonal-to-cubic phase transition. Transmission electron microscopy shows that the phase transition is accompanied by an interface reaction at the oxide/Si(111) boundary. The resulting cubic (111) low-temperature praseodymium sesquioxide film is single crystalline and exclusively shows B-type stacking. The 180° rotation of the cubic oxide lattice with respect to the Si substrate results from a stacking fault at the substrate/oxide boundary.