本實驗利用雷射光泵探系統(pump and probe laser system)於不同厚度之Ge2Sb2Te5相變化薄膜上寫下記錄點矩陣，欲分析在改變膜層厚度條件下，記錄點之光學反射訊號及表面形貌的改變。實驗中經由以下幾點進行分析：(a)、雷射光探測系統，可藉由光學反射強度進而了解記錄點不同相態(phase state)之改變關係；(b)、透過原子力顯微儀(atomic force microscopy)，可知記錄點表面的形貌(surface topography)起伏與變化，藉此了解雷射光束對相變化材料造成之物理形變為何；(c)、透過導電式原子力顯微儀(conductive-atomic force microscopy)，可知記錄點表面之導電性強弱，藉以分析不同相態之記錄點電性為何；(d)、透過歐傑能譜(Auger electron spectrum)分析，可對樣品表面進行元素成分分析，探討實驗中之表面氧化(surface oxidized)及不連續缺陷區域(defect of surface discontinuity)議題；(e)、透過加熱平台(heating stage)，在加熱下進行原子力顯微儀掃描，可得不同溫度下，寫下記錄點表面變化情形及相變化薄膜電性之改變。

In this study, we first investigate the optical response on phase-change material Ge2Sb2Te5 with an optical pump-probe system (Static tester, Optica co.). From the CCD images and reflectance of recorded mark matrix, the process of recording mark formation and the reflectance change can be analyzed and categorized. An Auger electron spectrum (VG Scientific,Microlab 350.) is also applied to analyze the component and oxidization of different types of recording marks.
For further understanding of the phase-change state of recording marks, we use a conductive atomic force microscope (C-AFM) with a heating stage (Asylum Research co.) to investigate the topographic change and the surface current distribution of recording marks on phase-change material at different temperature. From the experimental results, the process and the phase transition of recording marks on phase-change material Ge2Sb2Te5 can be obtained to have the further usage in ultra-high density recording.

[1]. 蔡定平，林威志，“近場光碟片最近的發展”，光訊，第八十七期，14-20頁 (2001).

[2]. 劉威志，林威志，蔡定平，“高密度近場光碟片”，物理，第二十三卷第二期 ，335-345頁 (2001).

[3]. S. R. Ovshinsky, “Reversible Electrical Switching Phenomena in Disordered Structures,” Phys. Rev. Lett. Vol.21, 1450 (1968).

[4]. F. Jedema, “Designing optical Media of the future,” News&Reviews, Nature Materials, Vol. 6, February (2007).

[5]. 徐豪汶，“鍺銻碲相變化奈米薄膜之奈米尺度光熱性質的研究”，碩士論文，中央大學物理研究所 (2006).

[6]. R. Kojima, S. Okabayashi, T. Kashihara, k. Horai, and N. Yamada, “Potential of Ge-Sb-Te phase change optical disks with high speedoverwrite ability,” Optical Data Storage Topical Meeting, ODS. Conference Digest (1997).

[7]. T. Ohta, “Phase-Change Optical Memory Promotes the DVD Optical Disk,” J. Opt. Adv. Mat. Vol. 3, 609 (2001).

[8]. S. K. Lin, I. C. Lin, and D. P. Tsai, “Characterization of nano recorded marks at different writing strategies on phase-change recording layer of optical disks,” Optics Express, Vol. 14, Issue 10, 4452-4458 (2006).

[9]. Y. Yang, C. T. Li, and S. M. Sadeghipour, “Thermal characterization of dielectric and phase change materials for the optical recording applications,” Journal of Applied Physics, Vol. 100, 024102 (2006).

[10]. M. Born, E. Wolf. Principles of optics, Oxford. Pergamon (1959).

[11]. T. Nonaka, G. Ohbayashi, Y. Toriumi, Y. Mori, and H. Hashimoto, “Crystal structure of GeTe and Ge2Sb2Te5 meta-stable phase,” Thin Solid Films, Vol. 370, 258-261 (2000).

[12]. N. K. Abrikosov and G. T. Danilova-dobryakova, and I. A. Nauk, “Phase-change materials: Designing optical media of the future,” Nature Materials, Vol. 6, 90-91 (2007).

[13]. N. Yamada, E. Ohno, K. Nishiuchi, M. Takao, and N. Akahira, “Rapid-Phase transitions of GeTe-Sb2Te3 pseudobinary amorphous thin films for an optical disk memory,” J. J. Appl. Phys. Vol. 69, 2849 (1991).

[14]. T. Matsunaga, N. Yamada, and Y. Kubot, “Structures of stable and metastable Ge2Sb2Te5, an intermetallic compound in GeTe-Sb2Te3 pseudo-binary systems,” Acta Cryst. B. 60, 685 (2004).

[15]. N. Yamada, T. Matsunaga, “Structure of laser-crystallized Ge2Sb2+xTe5 sputtered thin films for use in optical memory,” J. J. Appl. Phys. Vol. 88, 7020 (2000).
[16]. T. Matsunaga, and N. Yamada, “Crystallographic studies on high-speed phase-change materials used for rewritable optical recording disks,” J. J. Appl. Phys. Vol. 43, 4704 (2004).

[17]. Z. Sun, J. Zhou, and R. Ahuja, “Unique melting behavior in phase-change materials for rewritable data storage,” PRL 98, 05505 (2007).

[18]. C. Peng and M. Mansuripur, “Measurement of the thermal conductivity of erasable phase-change optical recording media,” Optical Society of America Appl. Opt. Vol. 39, 2347-2352 (2000).

[19]. P. K. Khulbe, “Crystallization behavior of as-deposited, melt quenched, and primed amorphous states of Ge2Sb2.3Te5 films,” J. J. Appl. Phys. Vol. 88, 3926 (2006).

[20]. W. K. Njoroge, “Density changes upon crystallization of Ge2Sb2.04Te4.74 films,” J. Vac. Sci. Technol. A20(1), 230 (2002).

[21]. R. Zallen, “Improved Pinning Center Morphology in HTS with Order-of-Magnitude Increase in Jc and Bpin Compared to Columnar Pinning,” The Physics of Amorphous Solids (John Wiley and Sons, New York) (1983).

[22]. V. G. Karpov, Y. A. Kryukov, S. D. Savransky and I. V. Karpov, “Nucleation switching in phase change memory,” Applied Physics Letters Vol. 90, 123504 (2007).
[23]. M. O. Thompson, G. J. Galvin, and J. W. Mayer, “Melting temperature and explosive crystallization of amorphous silicon during pulsed laser irradiation,” Physical Review Letters, Vol. 25, number23, June (1984).

[24]. C. Peng, L. Cheng, and M. Mansuripur, “Experimental and theoretical investigations of laser-induced crystallization and amorphization in phase-change optical recording media,” American Institute of Physics, s0021-8979(97)07821-3 (1997).

[25]. T. Tadokoro, T. Saiki, K. Yusu and K. Ichihara, “High-resolutin examination of recording marks in phase-change media using a scanning near-field optical microscope,” J. J. Appl. Phys. Vol. 39, 3599-3602, part1. No. 6a, June (2000).

[26]. 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,” J. J. Appl. Phys. Vol. 38, 1698-1700, part1, No. 3B, March (1999).

[27]. V. A. Kolobov, P. Fons, A. I. Frenkel, A. Ankudinov, J. Tominaga, and T. Uruga, “Understanding the phase-change mechanism of rewritable optical media,” Nat. Mater. Vol. 3, 703 (2004).

[28]. 高宗聖，“氧化鋅複合材料奈米薄膜之近場超解析結構”，碩士論文，台灣大學物理學研究所，(2004).

[29]. M. Mansuripur, J. K. Erwin, W. Bletscher, P. khulbe, K. Sadeghi, X. Xun, A. Gupta, and S. B. Mendes, “Static tester for characterization of phase-change, dye-polymer, and magneto-optical media for optical data storage,” Appl. Opt. Vol. 38, 7095 (1999).

[30]. P. K. Khulbe, T. Hurst, M. Horie, and M. Mansuripur, “Crystallization Behavior of Ge-Doped Eutectic Sb70Te30 Films in Optical Disks,” Appl. Opt. Vol. 41, 6220 (2002).