|Abstract: ||在本論文中，我們研製一系列高性能金屬-半導體-金屬式氮化鎵系氫氣感測器。在這一系列金屬-半導體-金屬式氮化鎵系氫氣感測器中使用到具有明顯催氫特性之金屬鈀、金屬鉑，與不具明顯催氫反應之金屬金。金屬鈀與金屬鉑被選做為製作元件是因其對於氫氣催化的卓越能力，而半導體方面則選用大能隙的(~3.4 eV)氮化鎵作為基材。在實驗中，上述所製作出的感測元件都置放於可變溫常壓的不鏽鋼腔體中，在固定流量下(500 ml/min)通入不同濃度的氫氮混合氣。進以量測包含感測響應、穩態反應變化量、以及暫態反應的時間，和計算如蕭特基能障變化量等重要參數。 基本型金屬鈀式的氫氣感測器具有不錯的感測響應(~175)、兩端對稱的感測特性、很短的反應時間、高穩定性及較寬的偏壓範圍。但為了提升感測響應倍率，以及進一步證明反偏端的感測機制與在受控溫度下的感測反應，我們提出多重型金屬-半導體-金屬氫氣感測結構。由於金屬鉑比金屬鈀在氮化鎵基板上有更優秀的感測響應(~9.85104)，對於氫氣的感測特性具有顯著的改善。另外，為了證明金屬-半導體-金屬結構氫氣感測器感測機制是由反偏端所控制，我們將反偏端蒸鍍上不具明顯催氫特性的金屬金，實驗證明偏壓在反偏端的無明顯催氫特性之金屬金通氫氣後，與另一端金屬鉑的催氫反應比較下，確無明顯反應。 另外，為了測試氫氣感測器在溫度變化下的感測特性，此多重型金屬-半導體-金屬感測結構在量測時加上了溫度變數，以擷取因溫度所造成的各項感測參數。最後，此多重型金屬-半導體-金屬氫氣感測結構最終的目的是要利用其本身的電流特性消除因溫度上升而造成的錯誤偵測警報。 根據實驗量測的成果展現，說明了這些研製的元件可適用於高性能感測器及高速積體化感測系統。 |
In this thesis, a series of high-performance GaN based Schottky metal-semiconductor-metal hydrogen sensors are fabricated and studied. There are two kinds of different fabrications, the first kind of hydrogen sensing metal is Palladium, and the second kind of hydrogen sensing metal we choose is Platinum and Gold. Pd and Pt are employed as sensing metal due to its excellent catalytic activity towards hydrogen gases. GaN is served as sensing platforms because of its larger bandgap than that of Si-based materials. In our experiment, the hydrogen sensors will put on home made variable temperature stainless steel chamber, under the fixed flow (500 ml/min) of several kinds of different concentrations H2 in N2 gas will be use. The sensing responses, EBH (effective barrier height) variations, static sensing variations, and transient responses of these sensors measured under different hydrogen concentrations have also been presented. The studied fundamental MSM Pd sensor exhibits some merits on good sensing response (~175), symmetrical sensing characteristics, short dynamic response time, nice stability, and widespread voltage regime. But, in order to ameliorate the sensing performances and further prove the sensing mechanism was decide by reverse side of MSM hydrogen sensor, and testing in variable temperature environment, we present a new functional structure of hydrogen sensor that call multiple metal-semiconductor-metal hydrogen sensor. For ultra-high sensing response (~9.85104), and improving the sensing characteristics, Platinum is better than Palladium. Moreover, to prove the sensing mechanism was decided by reverse side of MSM hydrogen sensor, Aurum was formed by thermally depositing on the reverse side of MSM hydrogen sensor. Based on experimental results, Aurum was formed by thermally depositing on the reverse side of MSM hydrogen sensors which haven’t conspicuous catalytic capability with hydrogen molecule in general range of temperature. Furthermore, To obtain all the sensing parameters from hydrogen sensors in the variable temperature environment, the samples were systematically tested at a range of temperature from 25ºC to 90ºC and H2 concentration from 49.1 to 4890ppm using an HP4145B semiconductor parameter analyzer. Finally, we expect the use of the bidirectional and unidirectional sensing properties removes false alarms due to ambient temperature variation. Based on experimental results, these studied devices provide the promise for high-performance sensors, and high-speed devices integrated system applications.