以Polyimide高分子材料和NafionTM作為REFET感測層之研究

Abstract

離子感測場效電晶體（ISFET）最早是由P.Bergveld在1970 年所提出的，其結構是將傳統的金氧半場效電晶體中的金屬閘極以待測溶液與參考電極所取代之。元件的電性會隨著溶液的不同而產生變化，同時我們也可藉由電性的變化來判定溶液的性質，我們在此以酸鹼離子感測器做探討。

本論文以找到最好的REFET為目標，在本篇論文中我們使用高分子聚合物 Polyimide和Nafion兩種材料，利用不同的組合結構覆蓋在ZrO2-pH-ISEFT的閘極絕緣層上，來修飾原本對氫離子有高靈敏度的ZrO2-pH-ISEFT 變成一個對氫離子靈敏度極低的參考電晶體(REFET)，這個使用Nafion 與Polyimide混合物的參考電晶體(REFET) 可以有很低的靈敏度7.5 mV/pH，為了確認此結構對pH緩衝液的抵抗力，我們也對此混合物結構對做閘極電壓漂移的研究，六小時的量測結果顯示，閘極電壓漂移為1.28mv/hr，最後我們將REFET/ISFET使用虛電極(Pt)量測結果顯示可以有54.47 mV/pH。

The ion-sensitive field effect transistor (ISFET) was first introduced by P.Bergveld in 1970. The metal gate is replaced by a reference electrode and the electrolyte. The electric characteristics are changed by different kinds of electrolyte , and we can distinguish the properties of electrolyte .In this study we examine pH-ion-sensitive field effect transistor.

The present paper take finds best REFET as a goal, we uses high polymer Polyimide and the Nafion two kind of materials in this paper, The different membrane has been coated on over the ZrO2 gate insulator surface of an ISFET. We apply the Nafion mix Polyimide structure to modify the ISFET sensing layer and successfully make the high H+ sensitivity ZrO2-pH-ISFET become a low H+ and Na+ sensitivity REFET. From the experimental results, the H+ sensitivity of ZrO2-pH-ISFET can be decreased to 7.5 mV/pH . We want to test this structure chemistry resistibility. We study the drift phenomenon in this structure. In the measurement with of 6 hours the gate voltage drift was 1.28mv/hr. When in differential ISFET/REFET with QRE (Pt) measurement, the H+ sensitivity will be 54.47 mV/pH .