13 research outputs found
Nonlinear optical probing of nanocrystalline orientation in epitaxial ferroelectric thin films
Epitaxially grown ferroelectric BaBi4Ti4O15 thin films were studied by optical second-harmonic (SH) generation using a femtosecond
titanium:sapphire laser at 800 nm wavelength. By varying both the
incidence and the azimuthal angle and registering the second-harmonic
intensity, a significant correlation was found between the azimuthal
dependence of the measured SH signal and the nanoscopic texture of the
samples, which was determined by electron microscopy and x-ray
diffraction. In particular, two different types of grains with
different crystallographic orientations generate different SH intensity
maxima with fourfold azimuthal symmetry, distinguishable from an
isotropic background due to a c-axis oriented main layer. This
correlation suggests the use of the SH technique for a purely optical
characterization of the film orientation and thickness. (C) 2002
American Institute of Physics
Charge Induced Pattern Distortion in Low Energy Electron Beam Lithography
Charge induced pattern distortions in low voltage electron beam lithography in the energy range of 1 to 5 kV were investigated. Pattern distortion on conducting substrates such as silicon was found to be small, while significant pattern placement errors and pattern distortions were observed in the case of electrically insulating substrates caused by charge trapping and deflection of the incident electron beam. The nature and magnitude of pattern distortions were found to be influenced by the incident electron energy, pattern size, electrical conductivity, and secondary electron emission coefficient of the substrate. Theoretical modeling predicts the electron beam deflection to be directly proportional to the trapped surface charge density and inversely proportional to the accelerating voltage