Interlayer couplings in silicon/oxide/nitride thin films via laser crystallizations

Abstract

The laser crystallization process that converts amorphous-Si to poly-crystalline-Si has attracted considerable attention owing to its wide industrial applications, such as active matrix organic light-emitting diode displays and photovoltaic devices. Herein, for thin-layer configurations of amorphous-Si/oxide/nitride deposited on a glass substrate, periodic surface ripples on Si induced by irradiation with a solid-state laser at an ultraviolet wavelength of 355 nm were examined using a guided-mode resonance theory. Modeling the periodic textures as one-dimensional gratings demonstrated several resonance peaks in the transmittance spectra, which were similar to the measured spectra. Furthermore, by varying the thickness of oxide (0-300 nm) and nitride (60-120 nm) sublayers, two resonance modes with separations of a few tens of nanometers were predicted for the transverse electric and transverse magnetic polarizations, respectively. The two-dimensional mode plots and electric and magnetic fields at the resonance wavelengths indicated that the mode couplings were mainly owing to the guided modes propagating in the Si and nitride layers. Because the peak positions and intensity of the resonance modes represent the figure-of-merit of the laser crystallization process, the resonance modes may be employed for the evaluation of the laser crystallization process; this will enable a more efficient evaluation compared to the current manual inspection of diffraction images by human eyes.