| Summary: | Since the discovery of CNTs, it was found that CNTs are superior to many materials in terms of electrical, mechanical and chemical properties. These advantages of CNTs have led to a surge of interest of using them in various fields and applications. One of the more promising applications is perhaps using CNTs as field emission electron source for field emission displays, and this provides the motivation for researching the field emission properties of CNTs.
Field emission properties of CNTs at room temperature have been researched extensively, but to understand in more detail, there is a need to know how temperature will affect the field emission properties of CNTs. To conduct this experiment, a suitable vacuum system and heater were needed. After various considerations due to limitations and restrictions of the equipment, the Beta Vacuum system, attached with a heater and a Keithley Source Measure Unit, was deemed to be suitable for this high temperature and vacuum experiment. After meeting necessary conditions, the field emission experiment of CNTs at various temperatures was conducted.
From the experiment, the I-V characteristics of CNTs at various temperatures were obtained. The analysis of this results proposed that the decreasing of turn-on voltage at elevated temperature can be attributed to the electrons gaining thermal energy, which leads to the decrease of the work function. Hence with a smaller work function, a lower electric field is needed for the electrons to be able to tunnel through the potential barrier and into vacuum.
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