State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology , School of Electronics and Information Technology, Sun Yat-sen University , Guangzhou 510275 , People's Republic of China.
ACS Appl Mater Interfaces. 2018 Jun 27;10(25):21518-21526. doi: 10.1021/acsami.8b00140. Epub 2018 Jun 13.
Thermo-enhancement is an effective way to achieve high performance field electron emitters, and enables the individually tuning on the emission current by temperature and the electron energy by voltage. The field emission current from metal or n-doped semiconductor emitter at a relatively lower temperature (i.e., < 1000 K) is less temperature sensitive due to the weak dependence of free electron density on temperature, while that from p-doped semiconductor emitter is restricted by its limited free electron density. Here, we developed full array of uniform individual p-Si/ZnO nanoemitters and demonstrated the strong thermo-enhanced field emission. The mechanism of forming uniform nanoemitters with well Si/ZnO mechanical joint in the nanotemplates was elucidated. No current saturation was observed in the thermo-enhanced field emission measurements. The emission current density showed about ten-time enhancement (from 1.31 to 12.11 mA/cm at 60.6 MV/m) by increasing the temperature from 323 to 623 K. The distinctive performance did not agree with the interband excitation mechanism but well-fit to the band-to-band tunneling model. The strong thermo-enhancement was proposed to be benefit from the increase of band-to-band tunneling probability at the surface portion of the p-Si/ZnO nanojunction. This work provides promising cathode for portable X-ray tubes/panel, ionization vacuum gauges and low energy electron beam lithography, in where electron-dose control at a fixed energy is needed.
热增强是实现高性能场致电子发射器的有效方法，通过温度和电压可以实现对发射电流和电子能量的单独调节。在相对较低的温度（即 <1000 K）下，金属或 n 型掺杂半导体发射器的场发射电流对温度的敏感性较低，这是由于自由电子密度对温度的弱依赖性所致，而 p 型掺杂半导体发射器的场发射电流则受到其有限的自由电子密度的限制。在这里，我们开发了一系列均匀的单个 p-Si/ZnO 纳米发射器，并展示了强烈的热增强场发射。阐明了在纳米模板中形成具有良好 Si/ZnO 机械结合的均匀纳米发射器的机制。在热增强场发射测量中没有观察到电流饱和。发射电流密度在温度从 323 K 增加到 623 K 时显示出约 10 倍的增强（从 60.6 MV/m 时的 1.31 mA/cm 增加到 12.11 mA/cm）。这种独特的性能与能带间激发机制不一致，但与能带间隧道模型吻合较好。强烈的热增强被认为得益于 p-Si/ZnO 纳米结表面部分的带间隧道跃迁概率的增加。这项工作为便携式 X 射线管/面板、离子真空计和低能电子束光刻提供了有前途的阴极，在这些应用中需要在固定能量下控制电子剂量。
