鍺銻碲相變化奈米薄膜之奈米尺度光熱性質的研究

Study of Nanoscale Optical-thermal Properties of Ge2Sb2Te5 Phase-change Nano Thin Film

徐豪汶(Hao-Wen Hsu)

指導教授 ： 陳宣毅 ； 蔡定平

國立中央大學/理學院/物理學系/碩士(2006年)

摘要

本論文利用雷射光泵探系統(pump and probe laser system)在Ge2Sb2Te5相變化薄膜上寫入記錄點，並研究在不同雷射光強度與脈衝時間的條件下，形成記錄點的過程並在此過程中，透過讀持續探測雷射光得到的反射強度變化，可用來分析記錄點寫入過程中，相變化記錄層的光學與熱學變化過程，鑑定與判別所形成的記錄點狀態。為了解析小於繞射極限的記錄點，並瞭解實際的記錄點大小，實驗中也採用導電式原子力顯微儀(C-AFM)來研究記錄點的電性及記錄點的表面形貌圖像，由導電式原子力顯微儀的結果，計算Ge2Sb2Te5相變化薄膜之有效作用比熱。在起始狀態為初始化狀態時，以雷射光功率為3mW，脈衝時間為50ns寫入紀錄點的實驗中，所計算出的薄膜之有效作用比熱為1.381 J/g-℃。

關鍵字

相變化光碟 ； 記錄點 ； 導電式原子力顯微儀 ； 雷射光泵探系統 ； 相變化材料 ； 硫屬合金

並列摘要

The purpose of the study is to utilize a pump-probe laser system, a static tester, to analyze the formation mechanism and the thermal properties of recorded marks on the thin film of the phase-change material Ge2Sb2Te5. The variation of reflectance on the phase-change recording layer can be acquired simultaneously as the recorded mark is being written. The information of optical reflectance on the interface of the phase-change recording layer can help observe marks written with either different powers or durations, respectively. The detailed change of reflectance provide us criterion to analyze both the formation mechanism of recorded marks and the state of recorded area on the recording layer. With the help of conductive-atomic force microscopy (C-AFM), not only the crystalline, as-deposited, and amorphous states can be characterized but also the area of recorded marks can be determined especially for the size of marks below diffraction limit. The area of recorded marks with respect to laser writing power or laser duration suggest that both writing power and laser duration have strong influence on the size of recorded marks. The effective specific heat can also be estimated by analyzing the relation between absorption power and area of recorded marks.

並列關鍵字

conductive AFM ； recording mark ； phase-change disk ； phase-change material ； Chalcogenide ； pump and probe laser system

參考文獻

[1] R. Zallen, The Physics of Amorpous Solids (John Wiley and Sons, New York,

[2] T. Ohta , “Phase-Change Optical Memory Promotes the DVD Optical Disk,” J.

[3] M. Libera, M Chen, “Multilayered Thin-Film Materials for Phase-Change

Erasable Storage,” MRS. Bulletin 15, 40 (1990)

[4] Henk van Houten and Wouter Leibbrandt, “Phase change recording,”