利用氧化提昇矽鍺奈米線生物感測器之靈敏度

Abstract

矽基材之奈米線在近年來已被廣範的研究。然而，就敏感度而言，矽鍺奈米線比矽基材之奈米線更有潛力，這是因為當同樣數量的待測物質鍵結於表面時，矽鍺奈米線有較大的電流變化。此外，我們發現敏感度會隨著鍺濃度增加而增加 (7%~30%)。 但是，製作高濃度之矽鍺奈米線有其困難度。因此，我們利用氧化的過程，使鍺由氧化層中析出，並獲得高濃度的矽鍺奈米線。經過900°C、2分鐘氧化後，我們可以發現低濃度( 7%、11%、20% )的矽鍺奈米線，其靈敏度均有提升。經過950°C、2分鐘氧化後，我們發現鍺濃度7%的奈米線的靈敏度繼續提昇，但鍺濃度11%的奈米線的靈敏度並沒有繼續增加，這可能是在氧化的過程中產生過多的缺陷所造成。

Si nanowires (SiNWs) have been studied for Bio-sensor in recent years. However, as far as sensitivity is concerned, SiGe nanowires are more promising than Si nanowires because of SiGe nanowires have higher change in drive current when the same chemical species bonding to surface of nanowire. In addition, we have reported the sensitivity increase with Ge concentration (7%~30%). But it is difficult to fabricate higher Ge concentration nanowire. Therefore, we utilize oxidation process to enhance Ge concentration in SiGe nanowire because Ge is rejected from the oxide during oxidation process. We found that the sensitivity of lower Ge concentration (7%~20%) nanowires were enhanced by oxidation process after the oxidation of 2min at 900°C. After the oxidation of 2min at 950°C, we observed that the sensitivity of Si0.93Ge0.07 nanowires were improved but the sensitivity of Si0.89Ge0.11 nanowires not increased. The reason maybe higher defect was formed during this oxidation process.