本論文將討論寬能隙直接半導體相關的特性研究，材料有三:分別是由碘蒸氣所成長的碘化銅 (CuI)，以及利用化學氣相傳導法所成長的II-VI族半導體硒化鋅 (ZnSe) 與碲化鋅 (ZnTe)，藉由能量散佈光譜儀 (Energy dispersive spectrometer, EDS) 和 X射線晶體繞射儀 (X-ray diffraction, XRD) 以及拉曼量測 (Raman) 分析，確認晶體的成分比例與確定成長出來的碘化銅為γ相立方晶系的碘化銅 (γ-CuI) 以及閃鋅礦結構半導體的硒化鋅 (ZnSe) 與碲化鋅 (ZnTe)，並對這些材料做光學與時間解析的量測。首先利用光激螢光實驗測得碘化銅 (CuI) 能隙為3.023 eV，當接觸氧的時候就會漸漸形成碘缺陷，所以我們也探討碘化銅 (CuI) 在室溫下接觸氧後的8小時與24小時的變化，接觸氧後的8小時碘缺陷的發光位置約為1.707 eV複合時間常數 τ1 與 τ2 分別為3.1 ns和11 ns，接觸氧後的24小時缺陷的位置為1.734 eV，複合時間常數 τ1 與 τ2 分別為34 ns和76 ns，從實驗可以得知缺陷剛形成的時候，其缺陷量還沒這麼多，複合時間常數還沒這麼長，24小時後缺陷量變多，所以複合時間常數變的很長，也驗證了碘化銅內部，由於碘易揮發的特質，容易形成缺陷。另外，本論文也將CuI鍍在GaSe上，使其成為異質接面元件，並對其進行光學實驗，在光激螢光實驗明顯地測得這個元件同時具備有CuI和GaSe的訊號存在，由時間解析實驗發現異質結構上的CuI和GaSe的能隙發光時間常數分別為0.203 ns和0.55 ns，而純CuI和GaSe分別為0.166 ns和0.4 ns，異質結構上的複合時間常數較純CuI和純GaSe還要長，因為在GaSe上鍍製CuI時，為界面間不同晶格大小所造成的應力，因此而產生差排，所產生的缺陷所導致。最後，利用光激螢光與時間解析實驗測得ZnSe在室溫下能隙位置約為2.68 eV，能隙複合時間常數為60 ps，低溫10 K時的能隙為2.79 eV複合時間常數為100 ps，複合時間常數特短，ZnTe在室溫下的能隙位置約為2.25 eV，複合時間常數為0.422 ns在低於120 K以下，由於晶體存在缺陷，所以能隙隨溫度變化會形成不規則移動的情形，複合時間常數很長為0.124 us，是為缺陷主導的發光現象，所以藉由光穿透光譜可測得ZnTe在低溫20 K到室溫的能隙訊號為2.39 eV到2.25 eV。

Copper (I) iodide (CuI), Zinc selenide (ZnSe) and Zinc telluride (ZnTe) crystals are wide direct bandgap semiconductors. The zinc blend structure of γ -CuI ,ZnSe and ZnTe are confirmed by energy dispersive spectrometer (EDS), X-ray powder diffraction (XRD) and Raman spectroscopy. Here, optical characterization of these crystals will be focused on emission properties and time-resolved photoluminescence (TRPL) analysis.
The bandgap of CuI is validated by photoluminescence (PL) analysis and the value is 3.023 eV. A comparison study of the CuI structure evolution atmosphere for 8 hours and 24 hours were also done. The PL emission of iodide defect of 8 hours is around 1.707 eV with lifetime of τ_1 and τ_2 of 3.1 ns and 11 ns. The emission of iodide defect after 24 hours in air is about 1.734 eV with τ_1 and τ_2 of 34 ns and 76 ns. With the increase of exposure time of CuI in air, the lifetime will also be longer. These phenomena prove that the iodine of CuI is easy to be vaporized and cause iodide defects
that occurred in CuI. Besides that, optical properties of a heterojunction device CuI/GaSe were studied. The device is made by CuI coating on GaSe. The heterostructure shows PL signal in both CuI and GaSe. From the TRPL analysis, the heterojunction of CuI and GaSe exhibit longer than that of pure CuI and GaSe. The longer lifetime is caused by the strain effect existed in the interface between the two crystals .At last, the PL and TRPL analyses of ZnSe show a photon energy of 2.68 eV and lifetime τ_1 of 60 ps under room temperature. At 10 K, the photon energy and lifetime τ_1 are increased to 2.79 eV and 100 ps, ZnTe shows a photon energy of 2.25 eV and lifetime τ_1 of 0.422 ns at room temperature. The analyses of PL and TRPL results of γ -CuI, ZnSe and ZnTe demonstrate potential capability of the materials for application in light-emitting devices.

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