水氣摻雜石墨烯之溫度感測器

Abstract

本研究用石墨烯作為感測元件以設計溫度感測器。由化學氣相沉積法成長之少層石墨烯，以手機保護貼為轉印基材將其轉印於玻璃上，製成溫度感測器，分別於大氣環境、真空環境、水氣環境三種環境中進行電阻對溫度變化的量測，並且藉由氫原子摻雜的前置步驟使石墨烯對水氣的吸附能力和吸附速率提升。電阻由Agilent 34411A之萬用電表量測，溫度由三段式高溫爐控制，最後經由計算得到溫度感測器於各環境下之溫度電阻係數(TCR)，並藉此分析其溫度感測的性質。 研究結果得到，一般大氣環境中重摻雜石墨烯之TCR值容易受環境的影響，其溫度感測能力不佳。真空環境中純質石墨烯為負溫度電阻係數(NTC)，且TCR值為定值，即感測器之靈敏度穩定。而水氣輕摻雜之石墨烯為NTC性質，其|TCR|隨溫度上升而變大，即溫度越高感測器之靈敏度越佳，至於水氣重摻雜時則為PTC性質。另外，氫原子摻雜後的水氣輕摻雜之石墨烯有最大的溫度感測靈敏度，其|TCR|於65 ℃時約為0.35 %/℃。

Graphene was taken as the sensing element to design a new temperature sensor in this study. Temperature sensor was made by the few-layer graphene which was grown by chemical vapor deposition (CVD) and then transferred to glass as the transfer substrate. We measured the relationship between temperature and resistance under normal atmospheric environment, vacuum environment and water vapor environment with hydrogen-doping preprocess respectively. Then we calculated temperature coefficient of resistance (TCR) of these cases and analyzed their temperature sensing behaviors. The experimental result indicates that the graphene has poor temperature sensing property under normal atmospheric environment. Intrinsic graphene under vacuum environment is negative temperature coefficient (NTC) and its sensitivity is stable. Lightly-vapor-doped graphene has NTC as well. However, heavily-vapor-doped graphene is positive temperature coefficient (PTC). And the |TCR| or the sensitivity of lightly-vapor-doped graphene increases as temperature rises. Furthermore, hydrogen doping will increase absorption capacity and absorption rate of graphene, which causes larger |TCR|, about 0.35 %/℃ at 65 ℃.