Quasi-Saturated Arsenic Concentration and Uniform Electron Emission by Regulating Thermal Oxidation of Si Nanotips

The improving of tip-to-tip electron emission uniformity in an array is one of the essential issues for the vacuum microelectronic/nanoelectronic applications. Here, we report the achieving of quasi-saturated ultrahigh arsenic concentration ( \sim 6.7\times 10^{{21}} /cm 3 ) at the Si nanotip apex, in the mechanisms of dopant segregation during the thermal oxidation and the limitation of arsenic solubility in Si. The tips with quasi-saturated high-level arsenic concentration possess a well tip-to-tip uniformity in surface work function. The measured work function for the tips in an array with saturated dopant concentration is in a narrow range of 4.347-4.371 eV (~2.1% fluctuation). This merit not only resulted in high emission current density (~418.36 mA/cm 2 ) from the devices at a relatively lower gate voltage but also brought well spatially uniform electron emission in an array. The work inspired vital insight into the interpretation for mechanisms in dopant density control and the improving of emission uniformity of the Si-tip array. It could be used as an essential approach to acquire high-performance Si-based vacuum electronic devices.