Theoretical Analysis of Self-Heating and Cooling Processes in the Pulsed Field Emission From ZnO Nanowire for Achieving High Emission Current

Quasi-one-dimensional (Q1D) nanowire field emitter arrays (FEAs) have important applications in vacuum microelectronics. Investigation on its pulsed field emission characteristics is important for not only avoiding self-heating-induced vacuum breakdown but also achieving high emission current. In this work, a model for quantitative calculation of the transient emission current and temperature distribution of individual nanowire during pulsed field emission has been established by considering the time-dependent thermal conduction equation. Taking ZnO nanowire as an example, the influences of the pulsewidth, the nanowire length, the nanowire radius, and the electrical properties of nanowire on its maximum transient emission current have been investigated. Besides, the cooling process is found to be mainly related on the nanowire length when the nanowire temperature is below 1000 K. By calculating the average emission current under different pulsewidths and duty ratios, it is found that its maximum is determined by the maximum emission current in the steady state that the nanowire is self-heating steadily to the critical temperature below the melting point. Finally, discussions for improving the emission current in different potential applications of FEAs are given. The results provide guidelines for designing Q1D nanowire FEAs.