本研究使用原子層沉積系統將氧化鋁(Al2O3)薄膜順應性(Conformally)地沉積至奈米碳管(CNTs)的表面上。奈米碳管材料對於水氣吸附後具有電阻變化的特性，而氧化鋁亦為相當優異之吸濕材料。因此，本研究進一步以奈米碳管為模具並將氧化鋁薄膜均勻的沉積其上，形成一奈米碳管/氧化鋁複合感測材料，藉此提升奈米碳管濕度感測器之元件靈敏度。並於感測材料下方整合多晶矽微型加熱器，增加排濕能力且避免水氣凝結。本研究之特色為: (1) 原子層沉積技術可將氧化鋁均勻沉積至叢聚奈米碳管中每一根碳管的表面；(2) 利用奈米碳管的結構特性使沉積之氧化鋁材料同時具有高體表面積之特色；(3) 利用氧化鋁材料之高吸濕能力與表面親水性以提高元件之靈敏度。量測結果針對純奈米碳管感測材料與奈米碳管/氧化鋁複合材料進行比較，其結果顯示，使用奈米碳管/氧化鋁複合材料其靈敏度具有7倍之提升。

This study presents a resistance-type humidity sensor using carbon nanotubes (CNTs) with Al2O3 coating. CNTs are typical materials for gas sensing and have the property resistance changing when absorbing moisture. Al2O3 is an excellent material for moisture absorption. Thus, this study uses the serpentine CNTs design integrated with Al2O3 conformal coating by Atomic Layer Deposition (ALD) process to form a CNTs/ Al2O3 composite for enhanced sensitivity of a humidity sensor. Features of this approach: (1) ALD Al2O3 to penetrate CNTs cluster and conformally coat on each CNTs surface; (2) High surface-to-volume ratio sensing structure offered by CNTs; (3) High moisture absorption capability offered by Al2O3 coating. Measurement results show that the sensitivity of the humidity sensors with 300°C annealed CNTs/ Al2O3 composite is ~7-folds higher than that of bare-CNTs.

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