Yujuan Zhang, Xiaoning Zhang, Wenjiang Wang, Chunliang Liu
Key Laboratory of Physical Electronics and Devices of Ministry of Education, Xi'an Jiaotong University, Xi'an, 710049, China.
J Nanosci Nanotechnol. 2012 Aug;12(8):6548-51. doi: 10.1166/jnn.2012.5421.
Porous silicon ballistic electron emission source with a structure of metal/porous silicon/Si/metal is obtained by anodization, rapid thermal oxidation, and sputtering. The microstructures of porous silicon layers are characterized by means of scanning electron microscope. The results show that disordered pores are formed at anodization current densities of 15 mA/cm2, 30 mA/cm2, and 45 mA/cm2 for 5 min, respectively. However, straight pores are formed at anodization current densities of 60 mA/cm2, and 75 mA/cm2 for 5 min, respectively. The electron emission characteristic of porous silicon ballistic electron emission sources is measured in vacuum. The results show that electrons emitted into the vacuum from the porous silicon samples with disordered pores. Under a bias condition, injected electrons from the substrate are accelerated by the strong electric field on the surfaces of the Si nanocrystallites in disordered pores, and then emitted into the vacuum through Pt film. However, no electron emission is observed in porous silicon samples with straight pores. It attributes to the lack of Si nanocrystallites in straight pores. So there is not accelerating tunnels enough for electrons. According to disordered or straight pores, we can estimate whether PS samples emit electrons or not.
通过阳极氧化、快速热氧化和溅射制备出具有金属/多孔硅/硅/金属结构的多孔硅弹道电子发射源。利用扫描电子显微镜对多孔硅层的微观结构进行表征。结果表明，在15 mA/cm²、30 mA/cm²和45 mA/cm²的阳极氧化电流密度下分别进行5分钟阳极氧化时会形成无序孔。然而，在60 mA/cm²和75 mA/cm²的阳极氧化电流密度下分别进行5分钟阳极氧化时会形成直孔。在真空中测量多孔硅弹道电子发射源的电子发射特性。结果表明，具有无序孔的多孔硅样品中的电子发射到真空中。在偏置条件下，来自衬底的注入电子被无序孔中硅纳米晶体表面的强电场加速，然后通过铂膜发射到真空中。然而，在具有直孔的多孔硅样品中未观察到电子发射。这归因于直孔中缺乏硅纳米晶体。所以没有足够的加速隧道供电子通过。根据孔是无序还是直的，我们可以估计多孔硅样品是否发射电子。
