Thermal Stress Induce Formation Nanogaps in Surface Conduction Electron Emitter

The different thermal stress in multilayer thin films during heating or freezing process can be employed to form the different morphologies: wrinkle, buckle, and crack. In this paper, a simple process based on above method is explored to induce and control Pd film to crack or delamination with crack which can be used as excellent electrode of surface conduction electron emitter. The crack size in Pd film can be limited into the range of 10 nm to 1.3 μm when the freezing time changes from 1 to 120 seconds. The cracks can also be achieved on the top of delaminate or buckles in Pd film by increasing temperature from room environment to 120°C. The crack position is promoted from 0 to tens microns and the crack angle adjusted from 0 to ∼ 60 degrees. Comparing the field emission characteristics of the different structured nano-gaps (plane crack and delaminating crack), larger crack angle is more conductive to tunneling electrons scatting out and the promoted electrodes decrease the distance between cathode-anode electrodes of electron emission. With the experiments of current-voltage properties of conducting mechanisms on a prototype device of surface conduction electron emitter, it is observed that the power consumption from cracks followed the delaminating process is remarkably lower than the simple plane cracks.