研究低維度材料在電光元件中的應用

Abstract

在本研究中，我們利用了藍寶石基板在不同晶軸具有不同熱膨脹係數的特性，成功的利用不同熱壓縮的程度，增加雙層二硫化鉬的能隙大小。而這種熱應力引發的局部能隙變化，可以使得在同一基板上二硫化鉬在小偏壓驅動下，會有一趨勢趨使光電子往平面基板移動，使其光電子更容易被電極給收集，並且透過理論計算，熱應變的模型使我們能夠預測不同角度的圖案化藍寶石基板上的帶隙移動行為。 從電性測量，我們發現錐形藍寶石襯底能夠在藍光照明下產生更多的光電流，另一方面，金字塔圖案藍寶石襯底在綠色和紅色光下具有出色的性能照明。透過三維電場模擬，不同波段的光子在不同結構中的光散射行為，可以主導不同的可見光波段對於雙層二硫化鉬的長成位置，最終造成不同的光感測行為。最後，我們使用基於雙層二硫化鉬的三維元件的優點，開發出在室溫下具有高響應性的新型光輔助型一氧化氮氣體傳感器。

In this study, we successfully demonstrated the thermally strained band gap engineering of molybdenum disulfide (MoS2) bilayers by different thermal expansion coefficients of patterned sapphire structures (PSSs). In particular, a blue shift in the band gap of the MoS2 bilayers can be tunable, displaying an extraordinary capability to drive electrons toward electrode under the smaller driven bias and the results were confirmed by the simulation. A model to explain the thermal strain in the MoS2 bilayers enables us to predict the band gap-shifted behaviors on PSSs with different angles. From electrical measurement, we found that cone-patterned sapphire substrate (CPSS) is able to generate more photocurrent under the blue light illumination, on the other hand the pyramid-patterned sapphire substrate (PPSS) has an outstanding performance under the green and red light illumination. Based on the 3D model simulations, the electric field distributions for the MoS2 pasted on different substrates showed that the superior sensitivity of MoS2-based photodetector can be greatly improved by the light scattering effect. Finally, we use those advantages of MoS2-based three-dimensional devices to develop a novel light-enhanced NO gas sensor with highly response at room temperature operating.