本論文針對氮化鎵材料之p-i-n光偵測器的相關製作與研究，光偵測器的結構包括有傳統p-i-n結構和在吸收層中加入低溫成長氮化鎵或氮化鋁的插入層之特性比較與討論。
　　在吸收層中間加入LT-GaN 的結構中，利用低溫成長的材料在其內部存在的缺陷能階來改變元件特性。存在這些缺陷能階中被捕捉的載子一旦被激發出來，可以造崩潰效應。因此造成內部增益的產生，使得元件有電流增益及光響應增加的現象。
　　在吸收層中間加入了LT-AlN的結構中，我們利用較大能隙的氮化鋁取代氮化鎵，而氮化鋁的高能隙特性可以作為電子的阻擋層。元件的暗電流可以有效的被抑制。在-40V逆偏電壓下和LT-GaN的結構相比暗電流小了3～4個數量級。利用LT-AlN的結構之元件，則可以有效的減少在長波長部分的光響應度，紫外光對可見光波段之鑑別率在高逆偏電壓下和LT-GaN的結構相比提高約2個數量級。暗電流的減少以及鑑別率的改善，是由於LT-AlN的材料具有較大的位能障所導致的。

We aims at fabricating and characterizing of GaN-based p-i-n ultraviolet photodetectors in the thesis. We have designed two variations, including p-i-n structure with low-temperature (LT)-GaN and LT-AlN interlayer(s) at middle of the absorption layer.
In the p-i-n structure with LT-GaN interlayer(s), it was found that the responsivity of the photodiode with LT-GaN interlayer can be enhanced at a small electric field due to the carrier multiplication effect. The carrier multiplication effect take place by the electrons collision with the carriers trapped in the defect level of LT-GaN. There might exist an internal gain, and the device has the increasing current gain with increasing reverse bias.
Comparing with the p-i-n structure with/without LT-GaN interlayer(s), it was found the we achieved smaller dark current and enhanced UV to visible rejection ratio from the structure with LT-AlN interlayer. The dark leakage current from the PDs with LT-AlN interlayer was shown to be about three orders of magnitude smaller than that for the traditional structure. The measured responsivity and UV to visible rejection ratio are 0.1 A/W and 1.25×102 at reverse bias of -40V. The rejection ratio is about two order magnitude lager than the structure with LT-GaN. This result can be attributed to the thicker and higher potential barrier of LT-AlN interlayer.

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