不連續金屬薄膜之光學特性探討

The optical properties of semicontinuous metal films

林昭輝(Jau-Huei Lin)

指導教授 ： 任貽均

國立臺北科技大學/電資學院/光電工程系研究所/碩士(2010年)

https://doi.org/10.6841/NTUT.2010.00147

摘要

本論文以電子槍蒸鍍系統製鍍不同填充率之不連續銀金屬薄膜，當不連續金屬薄膜濃度達到臨界閥值(percolation threshold) pc時，其薄膜性質會從介電質特性轉成金屬特性。利用光譜可以判斷金屬濃度何時達到臨界閥值。當濃度到達臨界閥值時，其光譜穿透率在紅外光區為一穩定值，且吸收達到約40%。
在結構上，以SEM觀察其表面形態。藉由對SEM圖片進行影像處理，可以計算出金屬濃度。由SEM圖形可以看出，到達臨界閥值時其連續路徑之變化。
藉由在不連續銀金屬膜上面鍍上一層介質層，之後再利用光學導納之理念反推薄膜的等效導納。由導納軌跡的趨勢，解釋金屬濃度變化，其介電質特性到金屬特性的相位轉換之成因。

關鍵字

不連續金屬膜 ； 臨界閥值 ； 光學導納

並列摘要

In this study, we fabricated semicontinuous silver film with different concentrations by electron-beam evaporation. As the metal concentration reach to the percolation threshold, the characteristics of semicontinuous silver film are changed from dielectric into metal.
The percolation threshold of metal films was determined by the optical spectrum. The optical transmittance of thin films at the percolation threshold is constant over a wide wavelength band in the IR region. And the optical absorption near the transition is found to be 40% and independent of wavelength.
The surface morphology of the samples was observed by scanning electron microscopy. The metal concentration for each scanning electron micrograph was calculated by using image-processing techniques. The connected pathway of metal film which varies with metal concentration can be observed from scanning electron micrograph.
The equivalent admittance of semicontinuous silver films can be retrieved by using characteristic matrix, which will explain the reason of phase transition from insulator to metal by the changes of metal concentration.

並列關鍵字

semicontinuous metal film ； percolation threshold ； optical admittance

參考文獻

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