Large-grain polycrystalline silicon films with low intragranular defect density by low-temperature solid-phase crystallization without underlying oxide
The solid-phase crystallization of an amorphous silicon film to polycrystalline silicon by a low-temperature (⩽600 °C) furnace anneal has been investigated in a suspended cantilever structure without underlying silicon oxide by transmission electron microscopy and Raman spectroscopy. The grain size of polysilicon increases up to ∼3.0 μm and the density of intragranular defects decreases one order of magnitude in the samples without underlying oxide, compared with those with underlying oxide. The main reasons for the high quality of the suspended structures are thought to be due to the lower stress in the films during crystallization and a reduced grain nucleation rate.
Defects in solid phase and laser crystallised polysilicon thin film transistors
Comparisons of polycrystalline silicon materials are made using both density of states measurements made on thin films transistors and transmission and scanning electron microscopy micrographs. We show that in solid phase crystallised materials, in-grain defects control electrical properties whereas in laser crystallised materials, it is grain boundaries.
Computer simulation of high‐resolution transmission electron microscopy images of Si/SiO2 interfaces
Cross‐sectional high‐resolution transmission electron microscopy (HRTEM) images of the crystalline Si/SiO2 interface have been computer simulated on the basis of various interface models in order to facilitate the interpretation of experimental HRTEM images. Continuous random networks of SiO2 have been constructed on crystalline Si substrates with different orientations and surface morphologies using plastic balls and spokes. The distortion energy introduced by artifacts in the model has been relaxed by modifying the atom positions, HRTEM images of the models have been calculated using the multislice dynamical electron scattering method. The apparent shift of the (111)Si/SiO2 interface into the SiO2 region has been observed due to the localization of first Si atoms in SiO2 region. The contrast of the crystalline Si image due to the amorphous SiO2 region in the wedge‐shaped bilayer structure of the Si/SiO2 interface has been obscured. The undulated (100)Si/SiO2 interface delineated with {111} facets has gi...