矽奈米線元件:歐姆與蕭特基介面比較

Abstract

近幾年來各式各樣的感測器已廣泛的被許多研究團隊做為研究，包含如何使元件的感測度提升。現今元件皆以微小化邁進，奈米線的縮小不僅可以降低元件體積，增加元件製作密度，更可利用元件之高表體比特性，提升元件對表面電位改變之靈敏度。本研究建立於之前的研究基礎上，同時建立N型以及P型的歐姆接面與蕭特基接面懸浮奈米線元件，並將奈米線(100奈米)的直徑經氧化方式成功的縮小到約22奈米左右。在考量與現今微電子製程的配合下，本研究選用鎳矽化物(Nickel-silicide)做為金屬/半導體蕭特基接面之金屬部分。金屬/半導體蕭特基接面元件與歐姆接面元件對載子傳輸之影響亦在本論文中探討；可以發現不論是N型或是P型結構的蕭特基接面元件，在元件表面鍵結帶電分子之後電性所表現出來的差異都比歐姆接面的元件還要優異。最後本研究運用帶電分子APTS與NTA鍵結在元件表面上，當表面接上不同之帶電分子時，將形成類似上閘極(Top gate)之結構，進而影響元件之電流電壓特性，據此來比較四種不同元件的感測度。無論從實驗與實作來看，蕭特基接面元件確實為一高靈敏度之感測元件，在未來應可成為生物感測器的主要元件之一。

In recent years, a variety of sensors with different sensing mechanisms have been proposed by many research teams to enhance the sensitivity in very low concentration. Modern electronic devices especially nanowire devices possess properties of high surface to volume ratio and high device density in device fabrication so that array of devices can be easily prepared. In this thesis, suspended N-type and P-type silicon nanowire devices of Ohmic contacts and Schottky contacts were prepared and characterized. The nanowire diameter are successfully reduced to ca. 22 nm via thermal oxidation. Carrier transport mechanisms of Metal/semiconductor Schottky contacts and Ohmic contacts devices were also evaluated and compared based on their transconductance. For CMOS compatibility, nickel was chosen to form nickel silicide and Schottky contacts with silicon. Finally, different charged molecules, NTA and APTS, were bound onto the surface of device to demonstrate the sensitivities of different devices. Based on sensitivities and sensing mechanisms of the four devices, the Schottly contact devices present higher sensitivity. It is believed that the nanowire devices with Schottky contacts are suitable for future applications.