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Optics Express

Optics Express

  • Editor: Michael Duncan
  • Vol. 14, Iss. 10 — May. 15, 2006
  • pp: 4452–4458
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Characterization of nano recorded marks at different writing strategies on phase-change recording layer of optical disks

Shih Kai Lin, I Chun Lin, and Din Ping Tsai  »View Author Affiliations


Optics Express, Vol. 14, Issue 10, pp. 4452-4458 (2006)
http://dx.doi.org/10.1364/OE.14.004452


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Abstract

Conductive-atomic force microscopy has been successfully used for characterizing recorded marks on commercial digital versatile disk and Blu-ray disk. Nano recorded marks beyond diffraction limit are imaged with high spatial resolution and excellent contrast of conductivity. The smallest mark size resolved is around 23.5 nm which is limited by background spots around 18.5 nm. The results of different optical power and writing strategy on the size, shape, and close packed writing process of recorded marks clearly show the opto-thermal response of phase-change recording layer.

© 2006 Optical Society of America

1. Introduction

2. Experimental setup

Two types of commercial phase-change optical disks, DVD+RW [14

14. 4X DVD+RW for data and video 4.7GB 120min, RITEK, 42, Kuan-Fu N. Road, Hsin-Chu Industrial Park, 30316, Taiwan.

] and write-once Blu-ray [3

3. Blu-ray disk 23GB, SONY, 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo 141–0001, Japan.

] optical disk, were used in the experiments. Recorded marks were prepared using commercial DVD+RW and Blu-ray optical disk drivers, respectively. A DVD dynamic optical disk-tester (Model DDU-1000, Pulstec, Japan) with a laser wavelength of 658±5 nm and numerical aperture of 0.65 was employed to record marks on phase-change layer of disks under different writing strategies as well. A simple and reliable mechanic striping procedure has been developed to separate the phase-change recording layer from the protective dielectric layer of the bonded disks. Conductive-atomic force microscopic images are scanned on the freshly cleaved phase-change recording layer subsequently.

Fig. 1. A schematic diagram of the scanning probe and recorded marks on phase-change layer of optical disk.

3. Results and discussions

A 5µm×5µm scan on AgInSbTe phase-change recording layer of a commercial DVD+RW optical disk [15

15. C. Peng, Lu Cheng, and M. Mansuripur, “Experimental and theoretical investigations of laser-induced crystallization and amorphization in phase-change optical recording media,” J. Appl. Phys. 82, 4183–4191 (1999). [CrossRef]

] is shown in Fig. 2. AFM topographic image and C-AFM intensity image acquired simultaneously are displayed in Figs. 2(a) and 2(b), respectively. The lower tracks shown in Fig. 2(a) are grooves of DVD optical disk where marks are recorded. The image also shows that the width of lands varies to provide low frequency wobble signals for the tracking of optical disks.

Fig. 2. 5µm×5µm three-dimensional AFM and conductive-AFM images acquired simultaneously on AgInSbTe phase-change recording layer of a commercial DVD+RW (4X) optical disk.

The average difference of height between lands and grooves in Fig. 2(a) is measured around 28±1 nm. Recorded marks in the grooves of Fig. 2(b) can be seen distinctly with the width of 354 nm and different lengths. The marks displayed in white color are the low conductive area of AgInSbTe phase-change layer. The contrast ratio of conductive current between marks and unmarked area is 2.82. Figure 2(b) evidently demonstrated the usefulness of C-AFM image of recorded marks on phase-change layers. C-AFM image can discern the length, width, intrinsic shape, perfection of boundary, covered area and conductive property of each individual recorded mark, and their relationship with respect to various writing strategies.

Fig. 3. 2.5 µm×2.5 µm AFM and conductive-AFM images acquired simultaneously on the recorded phase-change layer of a SONY Blu-ray optical disk.

For the understanding of the dependence of writing laser power on the mark size, recorded marks on a commercial DVD+RW (4X) optical disk are prepared by a dynamic optical disk tester (DDU-1000, Pulstec, Japan) with a constant linear velocity of 3.5 m/s and different laser writing power, 11 mW, 10 mW and 9 mW, respectively. Results of C-AFM images are shown in Figs. 4(a)–4(c). The recording spacing between marks is arranged to be 800nm to avoid the interference between adjacent marks. The average width of recorded mark displayed in Fig. 4(a) is 316±26 nm, which is smaller than the laser focusing spot size, 840nm. For the smaller writing power, 10 mW, the average width of marks shown in Fig. 4(b) is 208±14 nm, which is smaller than the diffraction limit, 616 nm. Results of Fig. 4(c) demonstrate the average width of 50±29 nm for 9 mW laser writing power. The smallest width of marks is around 23.5 nm which is limited by many (bright) spots with an average size around 18.5 nm in background. The area fraction of the spots in the background shown in C-AFM images is around 0.339. Resolving the spots in the background has never been reported through SEM or TEM images before. Apparently, the advantages of non-destruction, high spatial resolution, and excellent contrast on conductivity are the important capability of C-AFM.

Fig. 4. (a)–(c) 2.5 µm×2.5 µm C-AFM images on AgInSbTe phase-change recording layer of a commercial DVD+RW (4X) optical disk with different laser writing power, 11 mW, 10 mW and 9 mW, respectively. (d) schematic of optical writing threshold for recorded marks.

Fig. 5. (a) A 3µm×3µm AFM image on phase-change recording layer of a 4X DVD+RW optical disk. (b) C-AFM current intensity image acquired simultaneously with (a). Different spacing and shape of recorded marks can be observed. (c) Pulse train of writing strategy and the consequence of recorded marks are shown along with three-dimensional schematic of the areas above opto-thermal threshold plane. The size and shape of recorded marks can be affected by thermal interactions with adjacent marks.

For the first two recorded marks shown in left, the center-to-center distance between marks is 800 nm; therefore, it can be regarded as no overlap writing process. For the other four recorded marks with 400 nm spacing, three of the recorded marks are deformed due to the overlap of writing processes generated by the subsequent recording laser pulse. The crescent shape of recorded marks shown in Figs. 5(b) and 5(c) is formed because part of the mark is re-crystallized to the background. This is a typical example that size and shape of recorded marks can be closely affected by thermal interactions with adjacent marks.

4. Conclusions

Acknowledgments

The authors are grateful for the research support from the National Science Council of Taiwan, R.O.C., under project number NSC-94-2112-M-002-001 and the Ministry of Economic Affairs, R.O.C., under project number 94-EC-17-A-08-S1-0006. D. P. Tsai thanks the support from Center for Nano Science and Technology, National Taiwan University. Correspondence should be addressed to Din Ping Tsai, by phone: 886-2-3366-5100, fax: 886- 2-2363-9928, or e-mail: dptsai@phys.ntu.edu.tw.

References and links

1.

T. Ohta, K. Nishiuchi, K. Narumi, Y. Kitaoka, H. Ishibashi, N. Yamada, and T. Kozaki, “Overview and the future of phase-change optical disk technology,” Jpn. J. Appl. Phys. 39, 770–774 (2000). [CrossRef]

2.

R. Saito, F. Ito, Y. Yokochi, T. Saito, T. Ohira, H. Sato, and M. Itonaga, “Polarization-free Blu-ray disc/digital versatile disc compatible optical pick-up,” Jpn. J. Appl. Phys. 43, 4799–4800 (2004). [CrossRef]

3.

Blu-ray disk 23GB, SONY, 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo 141–0001, Japan.

4.

J. Tominaga, T. Nakano, and N. Atoda, “An approach for recording and readout beyond the diffraction limit with an Sb thin film,” Appl. Phys. Lett. 73, 2078–2080 (1998). [CrossRef]

5.

T. Fukaya, D. Buechel, S. Shinbori, J. Tominaga, N. Atoda, D. P. Tsai, and W. C. Lin, “Micro-optical nonlinearity of a silver oxide layer,” J. Appl. Phys. 89, 6139–6145 (2001). [CrossRef]

6.

D. P. Tsai and W. C. Lin, “Probing the near fields of the super-resolution near-field optical structure,” Appl. Phys. Lett. 77, 1413–1415 (2000). [CrossRef]

7.

W. C. Liu, C. Y. Wen, K. H. Chen, W. C. Lin, and D. P. Tsai, “Near-field images of the super-resolution near-field structure,” Appl. Phys. Lett. 78, 685–687 (2001). [CrossRef]

8.

W. C. Lin, T. S. Kao, H. H. Chang, Y. H. Lin, Y. H. Fu, C. Y. Wen, K. H. Chen, and D. P. Tsai, “Study of a super-resolution optical structure: polycarbonate/ZnS-SiO2/ZnO/ZnS-SiO2/Ge2Sb2Te5/ZnS-SiO2”, Jpn. J. Appl. Phys. 42, part 1, 1029–1030 (2003). [CrossRef]

9.

T. Tadokoro, T. Saiki, K. Yusu, and K. Ichihara, “High-resolution examination of recording marks in phase-change media using as scanning near-field optical microscope,” Jpn. J. Appl. Phys. 39, 3599–3602 (2000). [CrossRef]

10.

T. Kikukawa and H. Utsunomiya, “Scanning probe microscope observation of recorded marks in phase change disks,” Microsc. Microanal. 7, 363–367 (2001). [CrossRef]

11.

T. Luoh, J.-S. Bow, A. Peng, S.-Y. Tsai, and M.-R. Tseng, “Observation of recording marks in phase-change media using scanning electron microscopy channeling contrast image,” Jpn. J. Appl. Phys. 38, 1698–1700 (1999). [CrossRef]

12.

M. Miyamoto, A. Hirotsune, Y. Miyauchi, K. Ando, M. Terao, N. Tokusyuku, and R. Tamura, “Analysis of mark-formation process for phase-change media,” IEEE J. Quantum Electron. 4, 826–831 (1998). [CrossRef]

13.

B. J. Kooi, W. M. G. Groot, and J. Th. M. De Hosson, “In situ transmission electron microscopy study of the crystallization of Ge2Sb2Te5,” J. Appl. Phys. 95, 924–932 (2004). [CrossRef]

14.

4X DVD+RW for data and video 4.7GB 120min, RITEK, 42, Kuan-Fu N. Road, Hsin-Chu Industrial Park, 30316, Taiwan.

15.

C. Peng, Lu Cheng, and M. Mansuripur, “Experimental and theoretical investigations of laser-induced crystallization and amorphization in phase-change optical recording media,” J. Appl. Phys. 82, 4183–4191 (1999). [CrossRef]

16.

E. R. Meinders, H. J. Borg, M. H. R. Lankhorst, J. Hellmig, and A. V. Mijiritskii, “Numerical simulation of mark formation in dual-stack phase-change recording,” J. Appl. Phys. 91, 9794–9802 (2002). [CrossRef]

OCIS Codes
(210.4590) Optical data storage : Optical disks
(210.4770) Optical data storage : Optical recording

ToC Category:
Optical Data Storage

History
Original Manuscript: February 27, 2006
Revised Manuscript: May 5, 2006
Manuscript Accepted: May 6, 2006
Published: May 15, 2006

Citation
Shih Kai Lin, I Chun Lin, and Din Ping Tsai, "Characterization of nano recorded marks at different writing strategies on phase-change recording layer of optical disks," Opt. Express 14, 4452-4458 (2006)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-14-10-4452


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References

  1. T. Ohta, K. Nishiuchi, K. Narumi, Y. Kitaoka, H. Ishibashi, N. Yamada, and T. Kozaki, "Overview and the future of phase-change optical disk technology," Jpn. J. Appl. Phys. 39,770-774 (2000). [CrossRef]
  2. R. Saito, F. Ito, Y. Yokochi, T. Saito, T. Ohira, H. Sato, and M. Itonaga, "Polarization-free Blu-ray disc/digital versatile disc compatible optical pick-up," Jpn. J. Appl. Phys. 43,4799-4800 (2004). [CrossRef]
  3. Blu-ray disk 23GB, SONY, 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo 141-0001, Japan.
  4. J. Tominaga, T. Nakano, and N. Atoda, "An approach for recording and readout beyond the diffraction limit with an Sb thin film," Appl. Phys. Lett. 73,2078-2080 (1998). [CrossRef]
  5. T. Fukaya, D. Buechel, S. Shinbori, J. Tominaga, N. Atoda, D. P. Tsai, and W. C. Lin, "Micro-optical nonlinearity of a silver oxide layer," J. Appl. Phys. 89,6139-6145 (2001). [CrossRef]
  6. D. P. Tsai and W. C. Lin, "Probing the near fields of the super-resolution near-field optical structure," Appl. Phys. Lett. 77,1413-1415 (2000). [CrossRef]
  7. W. C. Liu, C. Y. Wen, K. H. Chen, W. C. Lin, and D. P. Tsai, "Near-field images of the super-resolution near-field structure," Appl. Phys. Lett. 78,685-687 (2001). [CrossRef]
  8. W. C. Lin, T. S. Kao, H. H. Chang, Y. H. Lin, Y. H. Fu, C. Y. Wen, K. H. Chen, and D. P. Tsai, "Study of a super-resolution optical structure: polycarbonate /ZnS-SiO2 /ZnO /ZnS-SiO2 /Ge2Sb2Te5 /ZnS-SiO2", Jpn. J. Appl. Phys. 42, part 1, 1029-1030 (2003). [CrossRef]
  9. T. Tadokoro, T. Saiki, K. Yusu, and K. Ichihara, "High-resolution examination of recording marks in phase-change media using as scanning near-field optical microscope," Jpn. J. Appl. Phys. 39,3599-3602 (2000). [CrossRef]
  10. T. Kikukawa and H. Utsunomiya, "Scanning probe microscope observation of recorded marks in phase change disks," Microsc. Microanal. 7,363-367 (2001). [CrossRef]
  11. T. Luoh, J.-S. Bow, A. Peng, S.-Y. Tsai, and M.-R. Tseng, "Observation of recording marks in phase-change media using scanning electron microscopy channeling contrast image," Jpn. J. Appl. Phys. 38,1698-1700 (1999). [CrossRef]
  12. M. Miyamoto, A. Hirotsune, Y. Miyauchi, K. Ando, M. Terao, N. Tokusyuku, and R. Tamura, "Analysis of mark-formation process for phase-change media," IEEE J. Quantum Electron. 4,826-831 (1998). [CrossRef]
  13. B. J. Kooi, W. M. G. Groot and J. Th. M. De Hosson, "In situ transmission electron microscopy study of the crystallization of Ge2Sb2Te5," J. Appl. Phys. 95,924-932 (2004). [CrossRef]
  14. 4X DVD+RW for data and video 4.7GB 120min, RITEK, 42, Kuan-Fu N. Road, Hsin-Chu Industrial Park, 30316, Taiwan.
  15. C. Peng, L. Cheng, and M. Mansuripur, "Experimental and theoretical investigations of laser-induced crystallization and amorphization in phase-change optical recording media," J. Appl. Phys. 82,4183-4191 (1999). [CrossRef]
  16. E. R. Meinders, H. J. Borg, M. H. R. Lankhorst, J. Hellmig, and A. V. Mijiritskii, "Numerical simulation of mark formation in dual-stack phase-change recording," J. Appl. Phys. 91,9794-9802 (2002). [CrossRef]

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