| 摘要 |
PURPOSE:To improve characteristics for repeated overwriting by constituting an optical recording layer of a Sb-Te-Ge alloy and adding a rare earth element to zinc sulfide for a heat-resistant protective layer. CONSTITUTION:The optical recording layer 3 consists of a Sb-Te-Ge alloy and heat resistant protective layers 2,4 provided on one or both sides of the recording layer 3 consist of zinc sulfide (ZnS)with a rare earth element added. By this constitution, adhesion strength between the protective layers 2,4 and the optical recording layer 3 comprising a Sb-Te-Ge alloy can be increased. The rare earth element is La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Tm, Yb, or Lu, and the add amt. is 5 - 40 mol%, more preferably 10 - 30 mol%. If the add amt. is less than 5 mol%, the effect of addition can not be expected, while over 40 mol%, laser absorption of the protective layer increases to reduce the contrast of recorded state from nonrecorded state. By this method, characteristics for repeated overwriting can be improved. |
