Uniformity Of Electron Emission Research Articles

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 ( $\sim 6.7\times 10^{{21}}$ /cm3) 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/cm2) 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.

Design and emission uniformity studies of a 1.5-MW gyrotron electron gun

We present the design and initial operation of a 96-kV 40-A magnetron injection gun for a 1.5-MW 110-GHz gyrotron. A critical parameter for the successful application of this electron gun is the uniformity of electron emission. The current-voltage curve of emission, at a series of temperatures, is measured. Analysis indicates that the work function of the emitter is 1.6 eV with a (total) spread of 0.07 /spl plusmn/ 0.01 eV. Measurement of the azimuthal emission uniformity with a rotating probe indicates that the work function variation around the azimuth, the global spread, is 0.04 /spl plusmn/ 0.02 eV. The spread due to local (microscopic scale) work function variations is then calculated to be 0.06 /spl plusmn/ 0.02 eV. Temperature variation can be ruled out as the cause of the observed emission nonuniformity.

Operation of a relativistic rising-sun magnetron with cathodes of various diameters

This paper presents results of an experimental investigation of a relativistic L-band (1.3 GHz) 10-cavity rising-sun magnetron with cathodes of various diameters. A major goal was to investigate the effect of the cathode diameter on the overall performance, mode stability and pulse shortening of this magnetron when operating at voltages of 100-500 kV and microwave peak power of P/sub /spl mu// /spl sim/ 100-700 MW. The largest levels of P/sub /spl mu// /spl sim/ 700 MW have been achieved, as expected, with cylindrical velvet cathodes. Mode structure and mode competition/switching for each cathode has been investigated in the entire range of operating magnetic fields. A cathode plasma expansion was found to be not the primary factor in a mode instability and pulse shortening of the magnetron investigated. Experimental results on effective magnetron diode gap, uniformity of electron emission, variation of the peak microwave power and microwave pulse duration with the cathode diameter and a correlation between the magnetron operating point and Buneman-Hartree curves are also presented and discussed.