(A) study on optical memory system using polymer deformation

Abstract

In the present work, the recording mechanism of compact disc- recordable (CD-R), which is a representative organic optical disk, were studied. To predict the recording mechanism of CD-R, the engineering analysis of the recording process has been carried out by using computer simulation. The optimum thickness of the dye layer was calculated by using matrix technique, and the temperature and stress distributions in the layers were estimated by using finite element method. From these numerical calculations, the curvature change of each interface was calculated and the dimensions of the deformed area were estimated. Based on the temperature distributions, the deformation temperature of each layer and the writing power of each deformation were predicted. To observe the thermal deformation and decomposition of the dye layer and PC substrate, CD-R was prepared by the conventional fabrication method. The dye layer was applied by a spin coating method and the gold reflective layer was formed by a sputtering method. After laser recording on the CD-R, each layer surface of the recorded CD-R was observed by the optical microscope, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The dimensions of the deformed area were obtained by AFM analysis. From the engineering analysis and the experimental observations, it was found that the recording mechanisms of CD-R consist of the three thermal deformation effects of the PC and dye layer, a bump, a pit and a bubble. To elucidate the effect of each deformation, the thermal deformation and decomposition of the dye layer were separately observed with a glass substrate CD-R by AFM analysis, and those of the PC were observed with a flat PC substrate CD-R. The effect of each deformation was interpreted by the recording characteristics, the carrier to noise ratio (CNR). The thermal behavior of the dye layer was investigated to estimate the property changes of the dye during laser recording. A glass substrate CD-R ...