直接寬能隙特性之III-V族化合物半導體如氮化鎵(GaN)、氮化銦(InN)等，廣泛應用於高亮度發光二極體、藍光雷射及太陽能電池等光電元件上。本研究中，以有機金屬氣相沉積(MOCVD)系統將氮化銦鎵(InxGa1-xN) (x=0.37，0.60及0.85)材料成長在藍寶石基板上，做為光檢測器的光吸收層。由於磊晶層間晶格缺陷導致光檢測器之光電特性不佳，因此本研究將在金半接面之間蒸鍍絕緣層或異質結構材料來改善光電特性； 另一方面，本研究以光激發濕式蝕刻技術(PEC etching)製作凹槽式電極結構來增加電場均勻性冀以提升元件特性。
第一階段研究結果顯示，因InxGa1-xN (x=0.37，0.60及0.85)材料磊晶品質不佳，致使金半金(MSM)結構光檢測器之暗電流偏高，且光電特性有待提升。因此，為降低暗電流特性，採取 Photo-CVD在InxGa1-xN表面成長絕緣層薄膜，製備金氧半 (MOS) 結構光檢測器元件。研究結果顯示，以Photo-CVD成長100 nm SiO2層的MOS元件與MSM結構相比更能提升光暗電流比達1.2~2.1倍，InxGa1-xN (x=0.37，0.60 及 0.85) 在偏壓3伏特時，MOS光檢測器之光暗電流比分別為6.7、10.7與49.7。由於光暗電流比之提升效果不佳,因此我們運用真空濺鍍方式在氮化銦鎵磊晶片上蒸鍍約100nm矽材料，製作金異半異質結構(hetrerojunction) 之光檢測器元件； 結果顯示，異質結構與金半金結構相比能夠更有效提昇光暗電流比達84.8~194.3倍；在偏壓為3伏特時，InxGa1-xN (x=0.37，0.60及0.85)異質結構光檢測器之光暗電流比分別為907.6、500.3與4583.8，且其響應波長值為470、640 及810 nm。此外，藉由蕭特基二極體之製備與量測，計算出蕭特基能障分別為0.92、0.76與0.69 eV。
第二部份，針對凹槽式電極結構應用於光檢測器之研究，凹槽式結構可以增強電場之均勻性來縮短光載子飄移到電極之時間與增加光載子之吸收量，進而提升元件效率。以光激發濕式蝕刻技術製備低蝕刻損害之凹槽式電極結構並可有效降低表面粗糙度達 31% 。研究結果顯示，與傳統平面式電極結構的金半金光檢測器相比，使用凹槽式電極結構更能夠提升光暗電流比達 55.8~94.4 倍，而與ICP乾式蝕刻技術相比則更能提升光暗電流比達2.66倍。 在偏壓3伏特時，InxGa1-xN( x=0.37，0.60及0.85 ) 凹槽式電極結構光檢測器之光暗流比分別為 480.6、228.8與2208.7。

Wild band gap material such as III-V compound are attracted in well electronic property of high chemical stability, high mobility, high thermal stability, and high breakdown voltage. The structure of InGaN based MSM photodetectors are epitaxied on sapphire substrate by MOCVD system. As result of the high lattice mismatch between InGaN and sapphire, the epitaxal quality is poor. Thus, the objective of this research is to design the appropriate device structure for InGaN based MSM, MOS, and heterojunction PDs to improve the device performance. On the other hand, InGaN based PDs with the recessed electrode is fabricated by PEC etching technique. Expectably, the device performance of recessed electrode PDs will be enhanced by the uniform electric field.
For the experiment one, the dark current of MSM PDs is very high due to the poor expitaxal quality. Then, InGaN based MOS PDs are fabricated in order to decrease the dark current. At a bias of 3 V, the photocurrent to dark current contrast ratio of InxGa1-xN (x=0.37, 0.60, and 0.85) is about 6.7, 10.7, and 47.9, respectively. However, the photocurrent to dark current contrast ratio of MOS PDs is only 1~2 times higher than MSM PDs that is due to the oxide layer decreases both of photocurrent and dark current in the meantime. Therefore, the thin SiO2 film is replaced with α-Si to enhance the photocurrent to dark current contrast ratio. For the Pt/α-Si /InxGa1-xN (x=0.37, 0.60, and 0.85) heterojunction PDs, the dark current is about 10-7 ~10-8 A, and the photocurrent to dark current contrast ratio is 84.8~194.3 times larger than MSM PDs, and the cut-off wavelength is 470, 640, and 810 nm, respectively. Then Schottky barrier height is measured about 0.92, 0.76, and 0.69 eV, respectively. The Pt/α-Si contact is confirmed to improve the performance of the InxGa1-xN (x=0.37, 0.60, 0.85) based heterojunction PDs.
For the experiment two, the recessed electrode MSM PDs is designed to enhance the device performance by the uniform electric field. The recessed electrode PDs is fabricated by the PEC etching technique, and the roughness of active layer is 31 % lower than as-grown material, which means the etching damage is low. For Pt/InxGa1-xN (x=0.37, 0.60, and 0.85) recessed electrode MSM PDs, the photocurrent to dark current contrast ratios are 480.6, 228.8, and 2208.7, respectively. It is found that the improvement of the photocurrent to dark current contrast ratios are 55.8~94.4 times higher for recessed electrode MSM PDs than planar MSM PDs. Compared with the ICP etching technique, it is found that the improvement of the photocurrent to dark current contrast ratio by PEC technique is 2.66 times higher than ICP process. Therefore, the design for recessed electrode MSM PDs by PEC etching is confirmed to enhance the device performance.

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