不同衬底对金刚石-石墨烯复合薄膜场发射性能影响研究

The influence of different substrates on field emission properties of graphene-diamond composite films

金刚石薄膜因其高导热性、负电子亲和势、低功函数和长期稳定性的特点被认为是一种很有潜力的场电子发射阴极材料。金刚石薄膜沉积在衬底上后,在不破坏金刚石薄膜自身结构完整性的前提下很难将其剥离。因此在场发射性能测试中一般是将金刚石薄膜和衬底作为整体测试,而衬底和金刚石薄膜间存在界面势垒,界面势垒对场发射性能的影响不可忽略。目前针对金刚石薄膜与衬底界面对场发射性能影响的研究相对较少,需要更多的关注和研究。分别以单晶硅、金属铌、金属钼为衬底,采用微波等离子体化学气相沉积(MPCVD)法生长制备了金刚石-石墨烯复合薄膜。对金刚石-石墨烯复合薄膜微观形貌、成分含量等进行了表征并研究了其场发射性能。研究结果表明,不同衬底对复合薄膜场发射性能影响显著,以金属铌衬底制备的复合薄膜表现出低开启场(E_(0)=2.5 V/μm)和较高发射电流密度(J@5.3 V/μm=1.9 mA/cm^(2))。此研究为获得更优场发射性能的金刚石-石墨烯复合薄膜提供了新的思路。

Diamond film is considered as a promising field electron emitter cathode material due to the high thermal conductivity,negative electron affinity,low work function and long-term stability.It is difficult to peel off the diamond film without destroying its structural integrity after the diamond film is deposited on the substrate.Therefore,the diamond film and substrate are generally tested as a whole during the field emission properties measurement.However,there is an interface barrier between the substrate and the diamond film,and the influence of the interface barrier on the field emission properties can not be ignored.At present,there are relatively few studies on the influence of the interface between diamond film and substrate on field emission properties,which needs more attention and research.In this work,the graphene-diamond composite films are fabricated by microwave plasma chemical vapor deposition(MPCVD),which the single crystalline silicon,metal niobium and metal molybdenum are used as substrates,respectively.The microstructure and composition of graphene-diamond composite films were characterized and the field emission properties were studied.The results show that different substrates have significant effects on the field emission properties of the composite films.The composite films fabricated on metal niobium substrate show low turn on field(E_(0)=2.5 V/μm)and high emission current density(J@5.3 V/μm=1.9 mA/cm^(2)).This study provides a new idea for obtaining graphene-diamond composite films with better field emission properties.