Field emission investigations on an array of LaB6 micro/nanostructures obtained using picosecond (Nd:YAG) laser treatment

An array of micro/nano structures have been obtained by laser surface treatment on sintered LaB₆ pellets employing a picosecond pulsed Nd: YAG laser at a pressure ~1times10^-3 mbar. The x-ray diffraction pattern of the laser treated pellet shows a set of well defined diffraction peaks, indexed to the cubic phase of LaB6 only. The scanning electron microscope studies reveal formation of micro and nano structures upon laser treatment. Field electron emission studies of an array (5 times 2) made on the LaB₆ pellet, treated with optimized laser fluence, have been performed in planar diode configuration under ultra high vacuum condition. The threshold field required to draw emission current density of ~10 muA/cm2 has been found to be ~2.3 V/mum and a current density of ~530 muA/cm² has been drawn at an applied field of 5.2 V/mum. The emission current at the preset value ~10 muA shows very good stability over the period of more than 3 hours. The present results emphasize the effectiveness of picosecond laser treatment towards fabrication of nanometric LaB₆ array emitter for high current density applications.