Pulsed laser deposition of HfO2 and PrxOy high-k films on Si(100)

Pulsed laser deposition was used to grow thin films of the high-k materials praseodymium oxide (PrxOy) and hafnium oxide (HfO2) on Si(100) due to its experimental simplicity and flexibility. Most important factors for technical application, such as film morphology and interface quality, were investigated by optical microscopy, atomic force microscopy and Raman spectroscopy. During the growth process typical splashes, originating from the laser–target interaction, are embedded into the growing layer. The size of these splashes appears to depend strongly on the laser wavelength (355, 532, 1064 nm). The microscopic morphology of layers of both materials shows a dependence on substrate temperature, which is much more pronounced in case of HfO2. Raman spectra of the films show relatively sharp phonon peaks, a single one for PrxOy and a rich spectrum for HfO2, clearly evidencing crystalline areas. This is corroborated by substrate Raman spectra which indicate a stressed interface, pointing to epitaxial PrxOy and HfO2 film growth, respectively, during the initial stages of growth.