Field emission properties of tungsten films exhibiting a rod-like structure

A thermal evaporation method was used for the deposition of tungsten films. The tungsten source was resistively heated to a temperature between 1810 and 2010 °C for the deposition. The resulting BCC α-tungsten film exhibits a rod-like structure and a highly preferred (2 0 0) orientation. This unique microstructure leads to field emission properties that are not only superior to the other forms of tungsten but also better than most of the other thin film emitters. A low turn-on field of 1.3 V/μm and an extremely high field enhanced factor of 398095 were obtained.