先進奈米元件結構於光感測與太陽能電池之研究

Abstract

在本論文中，使用硒化鎘量子點和金奈米粒子，透過離子作用力建構多層光感測奈米元件結構於矽基板上。在掃描式電子顯微鏡的觀察下，證明其結構成功生長於矽基板上。在製程上，利用lift-off技術成功在電極上定義出奈米粒子和量子點所要的圖樣。最後在結合硒化鎘量子點和金奈米粒子的奈米結構中，照射375 nm雷射光以及0.16 mW/ cm2日光燈後，在各種偏壓下有固定的光電流增加。在此研究中，在0.16 mW/ cm2日光燈照射下，可得到奈米元件的效率為0.67%，最大光電流為1.02nA，光電流體積密度1.334*10-23A/nm3，單位體積產生功率為2.45*10-25W/nm3。 在此同時，並做了三維方向的奈米元件探討(元件寬度、元件長度、元件層數)，實驗的結果發現元件長度的減少以及層數的增加有助於效率的提升，但是元件層數並非呈現線性的增加，而是在結構層數為八層之後開始會有飽和的現象。此外，以上的現象可以利用“奈米蕭特基二極體和電阻陣列”模型成功地解釋之，我們可以利用HSPICE去模擬此三維模型發現有同樣的現象。 最後，我們發現24層的金奈米粒子/硒化鎘量子點奈米結構之“太陽能電池效率”至少為先前金奈米粒子/硒化鎘奈米結構相關研究的5倍，且在我們理想的模型推導下，可以推得高效率太陽能電池。

In this work, we used CdSe QDs and Au NPs to construct the multi-layer photo-sensing nanodevice structures on a silicon substrate through ionic interaction. By the SEM views, the CdSe QDs and Au NPs successfully deposited on the silicon substrate. In the nanodevice process, the lift-off technology was successfully utilized to define the pattern of the Au NPs and CdSe QDs. Finally, the Au / CdSe nanodevices were illuminated by the 375 nm laser diode and the 0.16 mW/ cm2 daylight lamp. As a result, the multi-layer nanostructure composed of CdSe QDs and Au NPs, there was constant photocurrent increment to the current measured in the dark for each voltage bias after illumination with 375 nm laser and the 0.16 mW/ cm2 daylight lamp. In this work, under 0.16 mW/ cm2 daylight lamp illumination, the solar cell efficiency is 0.67%% . The maximum photocurrent is 1.02nA. The highest PVD (photocurrent volume density) is 1.334*10-23A/nm3. The power volume density is 2.45*10-25W/nm3. Meanwhile, the 3-dimension (width, length and the number of the layer) nanodevice efficiency investigation was executed. The shorter and thicker devices would benefit the performance of the solar cell efficiency. However, increasing the number of the layer would cause the saturation phenomenon when the number of the layer is more than eight. Besides, the above characteristics can be explained by the “nano-Schottky-diodes and resistor array” model. We can obtain the same phenomenon as using HSPICE to simulate the three dimensional model. In conclusion, we found that the“solar cell efficiency”of the 24-layered Au NPs / CdSe QDs nanostructure is at least 5 times better than the previous work of the Au NPs / CdSe QDs nanodevices. The solar cell can achieve high efficiency based on our model calculation.