電泳法沉積之微小化奈米碳管寬頻吸收器

Abstract

近年來，因為奈米碳管具有折射率相當接近空氣的光學特性，因此奈米碳管也可以運用在完美吸收器上。但是卻也因為奈米碳管為孔洞性材料且消光係數低的原因，如果被運用在完美吸收器上需要相當厚的厚度(大約100微米)，才能達到近乎完美的吸收。這限制對於光電元件的微型化整合與降低成本來說是相當不樂以見到的。因此，本論文提出利用電泳法製備奈米碳管的特性搭配共振腔結構來達到完美吸收的效果。實驗結果顯示，此結構在波長0.3微米到4.81微米之間可以達到平均吸收效率95%的寬頻吸收。值得一提的是，在維持高吸收的情況之下，此結構除了能減少整體厚度之外，也達到了全程低溫的製程(<120℃)。相信就以降低成本與寬頻吸收而言，本論文中所提出的結構是非常有潛力的運用在奈米光電元件上的。

In recent years, carbon nanotubes (CNTs) are used on perfect absorbers due to their optical property of close-to-air refractive index. However, because of porous materials and low extinction coefficients, CNTs requires a quite thick absorption layer (around 100 μm) to reach near perfect absorption. The large thickness of CNTs prohibits them from cost reduction and from realizing miniaturized integrated photonics. In this thesis, we use the characteristics of CNTs prepared by electrophoretic deposition (EPD) with resonant cavity structure to achieve perfect absorption. The experiment result reveals that an averaged absorption of 0.95 can be achieved over a broad spectral range from 0.3 μm to 4.81 μm. It is worth noting that, under the condition of maintaining the high absorption not only the total device thickness is reduced, but also the entire deposition process is done at low temperature (<120℃). We believe that this proposal is very promising for nano-photonic applications in terms of bandwidth, compactness, and the cost.