以CNT薄膜改善蕭特基二極體逆向偏壓之研究

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Title:	以CNT薄膜改善蕭特基二極體逆向偏壓之研究
Other Titles:	Study on the Effect of Reverse Bias of Increasing a Carbon Nanotubes Thin Films on GaN Schottky Diode
Authors:	李宜哲 LI,YI-CHE
Contributors:	苗新元電機工程學系
Keywords:	奈米碳管;蕭特基二極體;薄膜 Schottky diode;Thin Film;Carbon nanotube
Date:	2019
Issue Date:	2019-12-16T06:53:09Z (UTC)
Abstract:	從PN二極體問世後，漏電流一直都是一個受到高度討論的問題，因而改良出許多不同結構的元件如利用場板加長元件終止端的做法，與延伸出p型半導體重摻雜的保護環結構到JTE(Junction Termination Extension)的延伸結構等。同樣的問題在MOSFET上也有類似的狀況發生，MOSFET在大電壓的使用時，容易在元件中產生極大的電場而擊穿元件，但是要在MOSFET上製作PNP或NPN結構不只工序非常繁瑣也所費不貲。隨著科技發展，人們發現在MOSFET結構裡加入PNP或NPN結構的雙極性電晶體，去拉平其電場改善元件被擊穿的問題，因而發展出了IGBT這種擁有驅動電流小，導通電阻也很低的元件。因此我們想到利用蕭基二極體一樣擁有導通電壓低、允許高速切換的特性。在本實驗中以N型氮化鎵( n-type GaN，簡稱n-GaN )為基板，且為了達平坦化擊穿電場的目的，將奈米碳管(CNTs)噴塗於基板上形成薄膜後後再蒸鍍鎳(Nickel，Ni)、鈦(Titanium，Ti)、鋁(Aluminium，Al)三種金屬，比較所製作出蕭特基二極體之逆向偏壓與飽和電流，最後利用所量測之電流-電壓(I-V)的特性曲線來研究其元件特性。在本研究中發現，因奈米碳管是奈米級且零能階的良好導體，可以在元件施加逆向偏壓，使電場集中於終止邊緣的效應放大(Edge Termination)時，利用其特性將電場拉平，藉以提升逆向偏壓，比起場板(Field plate)、保護環(Guard Ring)等方式，只需要利用黃光微影定義圖型與蒸鍍的方式即可實現結構，縮短繁複的製程與節省成本。關鍵字：氮化鎵、蕭特基二極體、薄膜、奈米碳管 Since the advent of the PN diode, leakage current has always been a highly discussed problem, thus improving many different structural components, such as the use of field plate lengthening element termination, and the extension of the p-type semiconductor heavily doped protection ring and structure to a JTE (Junction Termination extension) extending structure. The same problem occurs in MOSFET. When a MOSFET is used for a large voltage, it is easy to generate a large electric field in the device and damage the device. However, fabricating a PNP or NPN structure on a MOSFET is not easy and costly. With the development of science and technology, it has been found that adding a PNP or NPN structure bipolar transistor to the MOSFET structure to flatten its electric field improves the breakdown of the component, thus developing a IGBT which having a small driving current and a very high on-resistance component. Therefore, we think that the use of the Schottky Barrier Diode has the characteristics of low turn-on voltage and high-speed switching.In this research, We used N-type GaN as the substrate, carbon nanotubes (CNTs) are sprayed on the substrate to form a thin film in order to achieve the purpose of flattening the electric field and then deposition of nickel, titanium, aluminum three metals, The reverse bias voltage and saturation current of the Schottky diode were compared. Finally, the characteristic curve of the measured current-voltage (I-V) was used to study the component characteristics. Finally, the characteristic curve of the measured current-voltage (I-V) was used to study the component characteristics. In this study, it’s found that CNTs thin film could flateen the electric field when a reverse bias is appield,and extend the voltage to 1000V max in experiment.Keywords: Gallium Nitride, Schottky diode, Thin Film, Carbon nanotube
Appears in Collections:	[Department of Electrical Engineering ] Master's Theses

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