高敏感度之矽鍺奈米生醫感測之研究與應用

Abstract

在這篇論文中我們探討矽鍺奈米線的感測能力之優缺點，並針對氧化過後之矽鍺薄膜做研究，緊接著將此結果應用於矽鍺奈米線並作感測能力之探論。 首先，先探討著矽鍺奈米線與傳統的多晶矽奈米線差異，矽鍺奈米線擁有優於傳統多晶矽奈米線較高的導通電流，但也擁有著較高的接觸電阻。 接著，我們利用傳統的薄膜電晶體元件做為我們測試結構，探討著不統的氧化條件下所造成的電流增益情況。越高的溫度及越長的時間氧化，都會造成其電流增益。此外，我們嘗試著在不同的氧化溫度與時間的條件已達到相同的氧化厚度，其電流增益也相同，此結果為相同的氧化厚度所導致的鍺析出也是一樣的。 其次，我們探討著不同的矽鍺濃度的奈米線的蛋白質感測。越高的鍺濃度擁有較高的感測能力，但是太高的鍺濃度其感測能力卻下降，我們推測是因為表面擁有過多的缺陷所導致。 再者，我們探討著矽鍺奈米線氧化厚的感測能力，在低濃度時，其感測能力隨著氧化溫度升高而提高，但是隨著濃度的提高其感測能力可能會因為過高的氧化溫度而下降，其原因可能為氧化溫度或時間過久使的鍺濃度超過一定值時會造表面缺陷上升。 最後，除了從材料或表面處理外，我們提出了一個新穎的結構來提升其奈米線的敏感度，利用雙層的高導通與低導通電特性，來有效的決定電流的路徑，如此在相同的電場變化下可擁有著較高的影響力，已得到較高的感測能力。

In this thesis, we concentrate our efforts on the advantage and disadvantage of SiGe nanowire and Poly-Si nanowire for bio-sensor. The behavior of oxidation for SiGe film was studied in the follows. The application of the SiGe oxidation was used to enhance the sensitivity in the end of thesis. First, we demonstrated the electric properties of SiGe and Poly-Si nanowires. The higher drive current is obtained for SiGe nanowire, but the disadvantage of the higher contact resistance appeared for SiGe nanowire. Secondly, the thin-film-transistor (TFT) was used to understand the increase of drive current after different oxidation conditions. The higher drive current obtained for the higher temperature, oxidation time and oxygen flow. Besides, the same oxide thicknesses were achieved by controlling the different oxidation time and temperature. The same drive current improves for the same oxide thickness. The reason come form the same Ge condensed after oxidation. Third, we studied the sensitivity of SiGe nanowire with different Ge concentration. The higher sensitivity was observed for the SiGe nanowire with high Ge concentration. However, the sensitivity decreased for the over-high Ge concentration. The reason may be that the higher defect appears on the surface. Finally, we used the Ge condensation technique on the SiGe nanowire for bio-sensor. The sensitivity improved for the SiGe nanowire with low Ge concentration after high temperature oxidation. However, the sensitivity decreased for SiGe nanowire with higher Ge concentration. It may be that the higher defect appears on the surface. In the end of the thesis, we introduce a novel structure to improvement the sensitivity. A double layer with high/low drive current is combined to achieve this point. The sensitivity improves under the same electric filed change by controlling the current through.