氮化銦場效電晶體液態感應器

Liquid-Phase Sensors Using InN Ion Sensitive Field Effect Transistor Structure

呂衍昇(Yen-Sheng Lu)

指導教授 ： 葉哲良

國立清華大學/電機資訊學院/電子工程研究所/博士(2009年)

摘要

本文將分子束磊晶術成長的單晶氮化銦(indium nitrite)製作成高靈敏度與高解析度的感應場效電晶體(ISFET)，並應用於偵測液體的陰離子濃度、酸鹼值與極性差異。薄膜(~10 nm)氮化銦與厚膜(1.2 m)鎂參雜型氮化銦底材被使用來提高電晶體的對閘極電壓的變化率，電晶體電流在閘極分別0.3 V 與0 V時，其電流變化率為 18% 與52%，遠大於厚膜(1 um)氮化銦(< 0.1%)，電晶體的大電流變化率可用於提高液相感應器的解析度。在液相感應器應用上，氮化銦感應器其材料表面對於對離子反應上，氮化銦表面正電性鍵接區可以選擇性物理吸附(physical adsorption)水溶液中的陰離子，並在接觸介面上建立電位(Helmholtz voltages) 此電位會依據水溶液離子體積濃度差異改變閘極表面電壓，進而影響場效電晶體的電流。另外，氮化銦離子場效電晶體對酸鹼值變化有極佳的反應，包括高靈敏度(58.25 mV/pH)、高解析度( <0.05 pH)、極短反應時間(<10 s)與極佳的信號穩定度與重複性。另外，對於極性溶液(polar liquid)的反應，包括甲醇、異丙醇與丙酮等，發現電流變化與溶液的偶極矩與介電係數比成線性相關，亦可用於判別液體極性的大小。

關鍵字

氮化銦 ； 離子感應場效電晶體

並列摘要

Ion selective field effect transistor (ISFETs) based on single crystal indium nitride (InN) film have been demonstrated for detecting pH values, anions and polarity in liquids. Three kinds of InN ISFETs containing 10-nm-thick, 1-um-thick and 1.2 um, magnesium (Mg) doped InN have been investigated by electrolyte-gate-biased current-voltage (IDS-VGS) measurements. IDS-VGS characteristics reveal that the a-InN:Mg ISFETs have a large (~52%) current variation ratio at a gate bias of 0.3 V with respect to the unbiased one, which is higher than that from the undoped InN ISFETs (~18% and <0.1% for 10-nm and 1-m-thick –c-InN epilayers, respectively). The ultrathin InN and a-InN:Mg ISFETs can also function as pH sensor with a high sensitivity (58.25 mV/pH), a high resolution (0.05 pH), and a short response time(<10 s). For anion sensing applications, the positively charged donors on InN surfaces selectively adsorbed anions and built Helmholtz voltages near the InN/solution interface. The InN ISFETs reveal remarkable selectivity, response time, signal stability, and repeatability for chloride ions. Chemical response to polar liquids including methanol, IPA and acetone, etc, shows a linear relationship with the ratio of dipole moment to dielectric constant of the liquid.

並列關鍵字

Indium nitrite ； InN ； InN:Mg ； ISFETs

參考文獻

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