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5.4 Future Applications 201
Table 5.6. Medium configuration of aperture-type super-RENS disk
layer material thickness (nm)phase optical constant
n k
substrate PC 0.6 × 10 6 – 1.56 0
protective layer SiN 170 – 2.35 0
mask layer Sb 15 crystal 3.52 5.48
amorphous 4.21 3.2
protective layer SiN 30 – 2.35 0
recording layer GeSbTe 15 crystal 3.97 4.41
amorphous 4.29 2.09
protective layer SiN 20 – 2.35 0
Mark writing Super-RENS Readout #2
P = 3.0 -9.0 mW P = 6.0 mW
w
r
v = 1.9 m s -1 V = 3.9 m s -1
Readout #1 Readout #3
P = 1.5 mW P = 1.5 mW
r
r
v = 1.9 m s -1 v = 1.9 m s -1
Fig. 5.41. Experimental analysis scheme to determine amorphous levels of both
mask and recording layers for super-RENS disk
(a) (b)
as-depo
V 1
V pp
V
2
as-depo: Initial level (before writing) CNR(dB)
V : Non-mark level (maximum)
1
V : Mark level (minimum)
2
V : Peak to peak (amplitude)
pp
Fig. 5.42. Two measured signals; signal amplitude with oscilloscope (a)and CNR
with spectrum analyzer (b)
read power. For short marks (200–400 nm) less than diffraction limit, the
signals appeared at the read power more than 5.0 mW. We define Sb-super-
RENS read power as 6.0 mW.
Wright power (recording level) consideration
Figure 5.44 shows a write power dependence of signal amplitude measured
for readout#1. Complete amorphous means the signal level that marks are