本實驗以熱注射的方法自行合成高品質，截面寬約為50-200nm，長度大於10-20m的鈣鈦礦奈米線，以研究光激發後載子的擴散行為。鈣鈦礦奈米線是一維半導體材料，在室溫下由於環境熱能高過激子的束縛能(binding energy)，所以在光激發過後無法形成激子，所以在共軛焦顯微鏡(confocal microscope)系統上經457 nm雷射激發後，奈米線當中會產生自由載子並進行擴散，本研究量測並解析載子之擴散長度(carrier diffusion length)及估算其載子遷移率(carrier mobility)。
本實驗透過電子倍增電荷偶合相機 (electron multiplying charge couple device, EMCCD)，分析載子擴散之螢光影像長度，與雷射光點強度輪廓圖的差異，確認兩者之間差異高達三倍以上，故採用光學量測方法直接測量擴散長度是可行的。並運用掃描式電子顯微鏡(scanning electron microscope, SEM)及原子力顯微鏡(atomic force microscope, AFM)，討論奈米線尺寸與載子擴散長度的關係，因而發現當奈米線寬度低於100 nm時，其載子擴散長度與奈米線本身寬度(截面積)有關，當寬度大於100 nm之後，奈米線寬度對載子擴散長度的影響則較為不明顯。
另外也討論基板環境的影響，使用本實驗室特有的14 nm厚度之大面積連續金膜作為基板，觀察當奈米線同時橫跨金膜及石英基板時，環境介電常數改變的影響；並且在金膜上會有鏡像電荷及基板屏蔽的效應出現，使得光致發光光譜於金膜上，較石英基板上有著3 nm的放光波長紅移；當奈米線於金膜上時，載子擴散長度也較石英基板上有著300-600 nm的減少。
最後，再藉著量測出的奈米線載子生命週期(carrier lifetime)，估算鈣鈦礦奈米線的載子擴散常數(diffusion coefficient)及載子遷移率，並與其他半導體材料比較，檢視此實驗方法有沒有可能為半導體產業，提供一項光學檢測技術，其可被視為非破壞性且不須額外製程的電性檢測方法。

In this experiment, high-quality perovskite nanowires are synthesized by hot injection. The width of the cross-section ranges from 50 to 200 nm while the length grows more than 10-20 m. Perovskite nanowires are one-dimensional semiconductors. Due to the low binding energy of exciton compared to the thermal energy of room temperature, only free carriers could be generated after photoexcitation. In this experiment, we measured and estimated carrier diffusion length and carrier mobility of perovskite nanowires.
Experimentally, the difference between the carrier diffusion length and the laser fluorescence intensity profile was analyzed by an electron-multiplying charge-coupled device (EMCCD) camera. The difference between the two was confirmed to be more than three times, making the optical measurement method feasible. After confirming the size of nanowires by a scanning electron microscope (SEM) and an atomic force microscope (AFM), the relationship between the size of the nanowire and the carrier diffusion length was further explored. The carrier diffusion length was found to be affected by the width (cross-section) of the nanowire itself when the width was below 100 nm. The effect of the nanowire width on the carrier diffusion length is less significant when the width is larger than 100 nm.
Furthermore, the effect of the external environment (substrate) was also investigated by spreading nanowires across the boundary between gold film and quartz substrate. The difference in environmental dielectric constant, mirror charges, and substrate shielding all affect the diffusion of carriers, especially on the gold film. We found that the carrier diffusion length is reduced by 300-600 nm when the nanowires are on the gold film compared to the quartz substrate.
Finally, the carrier lifetime of the nanowires was measured to estimate the carrier diffusion coefficient and carrier mobility of nanowires. We also compare our data with other semiconductor nanomaterials. The methodology can be considered a non-destructive and non-contact detection method for the semiconductor industry

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