本篇論文研究動機為製作能應用於光纖通訊全波段甚至延長到2,000nm的紅外波範圍，採用能隙小的鍺錫合金來製作金半金光檢測器來達到低暗電流與高響應度。
本文主要由兩大部分組成的。在第一部分，為了降低暗電流使用SiO2當絕緣層增加在金屬與半導體之間，形成較大的接觸能障，但是光電流也會下降。第二部分，選擇增加布拉格反射鏡在試片底部以及增加抗反射層在吸收層表面，目的都是為了收集更多入射光到吸收層，產生更多光電流，使得光響應度增加。在光響應方面，以指叉間隔及寬度5µm為例，在偏壓1伏時，金半金結構的光響應度為0.644A/W，增加布拉格反射鏡後上升到0.787A/W，增加抗反射層後增加到1.3A/W，表示增加抗反射層及布拉格反射鏡能有效增加光電流的產生。
最後，在偏壓1伏特下，歸一化光響應度量測實驗數據顯示截止波長成功地延伸至2,000nm附近，超越了鍺光檢測器的吸收極限1,550nm且能完整涵蓋光纖通訊中所有波段，證明鍺錫材料做為新型紅外線光檢測器的優勢。

The thesis focus on developing infrared photodetectors that cover the entire telecommunication windows. Narrow-bandgap GeSn is used to fabricate metal-semiconductor-metal photodetectors with low-dark current and high responsivity.
There are two sections in this thesis. In the first part, to reduce the dark current, the SiO2 layer is inserted in between metal and semiconductor to increase the barrier height, but with the expense of reducing the photocurrent. In the second part, the goal is to couple more incident light into the absorption layer, thereby increasing the responsivity. The experiment incorporates the distributed Bragg reflectors deposited at the bottom of GeSn substrate while placing the anti-reflection layer on the surface of the absorption layer. With the interdigital electrode spacing and width, both set at 5µm and with 1V bias applied, it was found the responsivities of the generic MSM structure, the MSM with DBR structure, and the MSM with AR layer structure were 0.644A/W,0.783A/W, and 1.3A/W, respectively. The measurement data show that these designs effectively enhance photocurrent and responsivity.
At 1V bias voltage, normalized responsivity shows that the photodetection range has been extended from 1,550 nm to over 2,000 nm, covering the entire telecommunication bands. Incorporating GeSn as a sensing layer offers one of the new alternative avenues for IR photodetection.

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