High-transfer-rate 4.7-GB DVD-RAM

Showed the feasibility of 4.7-GB DVD-RAM media for 5/spl times/ recording. In order to maintain compatibility with current 2/spl times/ drives, we reduced jitter in both 2/spl times/ and 5/spl times/ recording. The most important design concept is to control the crystal growth velocity and crystal nucleation frequency: the former should be reduced and the latter increased. To control these values, we prepared a medium having a Ge-Sb-Te recording film and a nucleation promoting film. It showed jitter lower than 10% in both 2/spl times/ and 5/spl times/ recording.