次波長金屬與金屬矽化物結構在光偵測器上的應用

The Study of Subwavelength Structure on Metal and Metal Silicide for Photo-Detector Applications

楊伯康(Pong-Kang Yang)

指導教授 ： 陳學禮

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.02197

摘要

金屬與半導體接面偵測器於由具有多項的優點而在偵測器領域中受到矚目。然而，表層金屬電極的高吸收特性與收光面積比例，仍有進一步改良的空間。金屬矽化物，本身與半導體製程相容性極高、具有低接觸電阻特性且與矽基板間可形成完整的金半接面；再配合其薄膜可透光的性質，於偵測器應用上逐漸嶄露頭角。儘管如此，矽化物擁有與金屬相同的高介面反射率與高吸收特性，是其偵測器在使用上的難題。有鑑於此，我們藉由引入抗反射結構與薄膜技術來改善，降低其表面反射，希冀達到提升入光量的效果。
對於一偵測器而言，最重要的莫過於載子的產生與導出，而此裝置與一般金半接面偵測器不同點在於：表層整面金屬收光區，不需指狀電極的的定義製程；再由表層結構的改變提升入光量，配合表層金半接面，應可萃取更多光電流，進而提升偵測器效率。
表面電漿，本身為一沿金屬與介電質接面傳遞的電漿波，在特定波段具有高穿透率是其最常被提及的特性。一般引發表面電漿波的方式除了以ATR(消逝全反射)理論外；便是製作一週期性結構使得入射光耦合成表面電漿波。此外，亦有相當多的文獻也提出在非週期性結構下的表面電漿行為。舉例而言，單一孔洞本身亦具有表面電漿現象是深入探討且證實的現象。因此，我們試著將一般傳統光偵測器上電極製作結構，探討製作結構後的電流變化。由量測的結果，我們也的確觀察到光電流增幅的響應。然而，在探討此增幅時，製作結構後本身透光量的增加與表面電漿對於週期結構的相依性都是必須考量的重點。我們希望透過結構的製作與表面電漿現象連結，將原本被電極覆蓋的收光區域可以更完善的被利用，藉此進一步提升偵測器的效率。

關鍵字

光偵測器 ； 表面電漿 ； 矽化物

並列摘要

It's worthwhile to pay more attentions on metal and semiconductor interface due to its several advantages for photo-detector applications. However, higher absorption of metal electrode and determination on ratio of active region still leave something behind. Metal silicide, an well-known and highly compatible alloy material in conventional fabrication process. Lower contact resistance and complete Schottky Interface formation with Si substrate are its intrinsic properties. On the other hand, we also take transmittance and reflectance of silicide thin film into consideration. Those gradually indicate great potential of silicdie on photo-detector applications . Though, due to higher reflection of silicide and ambient environment, we fabricate two dimensional antireflective structure to improve this critical situation.
As for a photo-detector, carrier generations and collections are the major concern. What we focus on here is that surface junction and collection areas. In other words, conventional step of metal finger definition can be curtailed within the fabrication process of silicide detector. Furthermore, the antireflection structure will enhance light penetration accompanying with metal-semiconductor interface junction. We believe that it provides a promising future to the field of photo-detection.
Surface Plasmon, an electromagnetic wave propagating along metal and dielectric surface. It's well known that surface plasmon will induce an extraordinary transmission showing dependence on wavelength. Generally speaking, there are two ways of exciting SPW(Surface Plasmon Wave). One is by use ATR thoery ; another is by fabricating periodic structure to induce extra wave vector. However, several researches have pointed out that surface plasmon phenomenon will exist even in a single nanohole. Therefore, we attempt to fabricate nanohole structure on conventional finger electrode and analyze the results of their difference. We find the excess current ratio is truly enhanced after nanostructure fabrication. Nevertheless, it can’t be ignored that the enhancement of excess current ratio is resulted from both light penetration and surface plasmon. By structure fabrication and surface plasmon basis, we consider that more utlilization of light, especially for the junction region covered with metal previously.

並列關鍵字

photodetector ； surface plasmon ； silicide

參考文獻

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