摻雜元素對相變化光碟的覆寫效應和記錄層微觀結構的影響

Abstract

由於多媒體資訊的蓬勃發展，數位多功能光碟(Digital Versatile Disks, DVDs)被譽為下一世代記錄媒體。本論文探討摻雜不同種類的元素於相變化光碟的記錄層中對碟片覆寫的訊號特性所產生的影響。在五種摻雜的元素中，少量的鉬摻雜於記錄層內可以改善光碟的覆寫訊號雜訊比和覆寫擦拭特性，尤其在低寫入功率時其效果更為明顯。透過電子顯微鏡的觀察可知，鉬元素的摻雜可以有效抑制記錄層的晶粒成長，使得碟片整體的訊號雜訊下降，因而獲得良好的訊號特性。此外，覆寫次數的實驗結果亦證明了鉬元素的添加使得可覆寫的次數增加至兩倍以上。在本實驗中亦建立一新的平面式電子顯微鏡試片製備方法，以便於進行微觀結構的觀察，詳細的製作過程和剝除溶液的使用將在論文中說明。

Digital versatile disks (DVDs) are expected to be the next generation data storage technology. In this article, the Ge-Sb-Te recording layer of phase-change optical disks was doped with various elements and their effects on overwriting signal characterizations were presented. Among the five different types of elements doped, it was found that by adding a small amount of molybdenum (Mo) into the recording layer (typically 0.5~1 % foil-to-target area coverage ratio during sputtering), the carrier-to-noise (CNR) ratio and overwriting properties of optical disks gained substantial improvement especially in the low writing laser power regime. Transmission electron microscopy (TEM) revealed that the Mo doping may effectively reduce the grain growth rate of recording layer so as to decrease the noise level. Moreover, the cycleability test indicated that the overwriting counts increased up to two times when Mo was added. Specimen preparation method for plan-view TEM observation was also established in this work. Detailed procedures and etching solution used are also described in this work.