隨著科技的發達，氫氣的應用越來越廣泛，因為氫氣具有爆炸性，因此監控氫氣已是現今一重要課題。與傳統氫氣感測器比較起來，本文所提之氫氣感測元件具有輕、薄、短、小等優點。
在本論文中，我們研製一系列砷化鎵肖特基接觸式氫氣感測器元件。主要重點在於研製具有高靈敏度以及寬廣氫氣感測範圍，其中包括了以砷化鎵為基底成長三種不同的主動層，接著以不同的觸媒金屬分別做成電晶體式以及肖特基二極體式氫氣感測器，分析在不同的氫氣濃度、不同的操作溫度下，感測元件的反應特性。
首先，我們製作了以鈀為觸媒金屬的砷化鎵金屬-絕緣層-半導體場效電晶體式氫氣感測器，本元件具有大的氫氣感測電流變化量、可在室溫下操作以及對氫氣反應速度快等優點。此外，由實驗得知，電晶體的轉導值會隨著氫氣濃度的增加而逐漸變小。
接著，我們製作了以白金為觸媒金屬的磷化銦鎵肖特基二極體式氫氣感測器，因為磷化銦鎵具有大的能隙，因此該元件可以操作在相當寬廣的溫度範圍。另外，我們分別在砷化鎵基板成長不同摻雜濃度的磷化銦鎵氫氣感測器，並測量分析其氫氣感應特性。
為了研究費米能階釘住效應對氫氣感測的影響，首先我們製作以鈀為觸媒金屬的磷化銦鎵金-半接面肖特基式二極體，並對其氫氣反應特性作量測與分析，並與具備氧化層之磷化銦鎵金-氧-半接面場效電晶體做比較。由實驗的結果與理論分析，我們得知具有界面氧化層結構的感測器無論在靈敏度、電流變化量以及與氫氣反應的時間都明顯比沒有氧化層之感測器優良。
在不同的觸媒金屬(如：鈀金屬和白金)的比較上，由實驗可以得知，以鈀為觸媒金屬的磷化銦鎵金-氧-半肖特基二極體式氫氣感測器在較低的氫氣濃度以及較低的操作溫度有較大的感測靈敏度以及電流變化量；相反的，以白金為觸媒金屬的氫氣感測器在較高溫及較高的氫氣濃度會有較佳的表現。
另外，我們亦製作了以鈀為觸媒金屬的砷化鋁鎵肖特基二極體式氫氣感測器，由於砷化鋁鎵具有大的能隙以及比磷化銦鎵材料較易成長氧化層等特性，因此元件的靈敏度、電流變化量等氫氣感應特性皆明顯獲得改善。

With the vast advance in scientific technology, the applications of hydrogen gas have spread over many fields. Since the hydrogen is a flammable and explosive gas, the monitor and detect the leakage of hydrogen gas is an importance issue. As compared with conventional hydrogen sensors, the advantages of our studied devices are small size and ease of fabrication.
In this dissertation, we present a series of hydrogen-sensing GaAs-based Schottky contact devices. The main concerns demonstrate high hydrogen detecting sensitivity and widespread operating temperature. Three different active layers, used as Schottky contact layers are grown on GaAs substrates. The different catalytic metals, e.g., Pd and Pt, are used as the gate material. These studied devices are investigated under different hydrogen concentrations and different operation temperature based on the transistor and Schottky diode type, respectively.
First, a novel Pd/oxide/GaAs metal-insulator-semiconductor field-effect transistor (MISFET) hydrogen sensor is fabricated and demonstrated. The studied device exhibits some remarkable advantages, including large current variation and short hydrogen response time under exposing in hydrogen condition at room temperature. In addition, it is know that, from the experimental results, the transconductance is reduced with increasing the hydrogen concentration.
Second, a new Pt/oxide/In0.49Ga0.51P Schottky diode hydrogen sensor is fabricated and demonstrated. Due to the relatively large energy bandgap of InGaP, the studied devices can be operated under widespread temperature regime. In addition, the hydrogen-sensing characteristics of the Pt/oxide/In0.49Ga0.51P Schottky diode hydrogen sensors with different doping concentration of active layer are measured and studied.
In order to study the influence of Fermi-level pinning effect and hydrogen sensing, the Pd/InGaP MOS and MS Schottky diodes hydrogen sensors are fabricated and systemically studied. From experimental results, it is known that the MOS type hydrogen sensor exhibits high hydrogen detecting sensitivity, larger current variation, and short hydrogen response time than that of MS type hydrogen sensor.
By comparing different catalytic metals (e.g., Pd and Pt), the Pd-InGaP Schottky diode exhibits larger current variation and barrier height change under low hydrogen concentration ambient. On the contrary, the Pt-InGaP Schottky diode shows better high-temperature performances and larger hydrogen detection regimes.
Finally, the catalytic Pd MOS Schottky diode hydrogen sensor based on an AlGaAs active layer is fabricated and investigated. Due to the larger energy bandgap and ease of forming the oxide layer, the hydrogen-sensing characteristics such as hydrogen detecting sensitivity and current variation are remarkly improved.

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