Molybdenum field emitter arrays (FEAs) fabricated by molding and a self-aligned gate process [1] have been successfully used to fabricate stacked-double-gate FEAs [2, 3], and to demonstrate high-acceleration field compatibility [4], and near infrared laser-induced field-emission [5]. For higher brightness cathodes, we are currently developing nanoscale (300nm emitters, 750 nm pitch) molded molybdenum FEAs. As emitter dimensions approach the grain size for sputtered molybdenum films, roughness in the metal grain structure, for example due to self-shadowing when coating topographic features, becomes increasingly significant for the FEA structures. Fig. 1 illustrates topographic roughening for a) coating of concave, pyramidal Si molds to make the emitters, and b) gate metallization coated over one convex emitter on a demolded FEA. During mold coating the roughness creates axial pores in the emitter tips which the subsequent evaporated and electroplated metal layers cannot fill. For gate apertures with diameter < 0.5 µm, the molybdenum grain structure distorts the aperture shape.
[1]
F. Pimpec,et al.
Nanosecond pulsed field emission from single-gate metallic field emitter arrays fabricated by moldinga)
,
2011
.
[2]
K. Jefimovs,et al.
Highly collimated electron beams from double-gate field emitter arrays with large collimation gate apertures
,
2011
.
[3]
H. Fink,et al.
Field-Emission Characteristics of Molded Molybdenum Nanotip Arrays With Stacked Collimation Gate Electrodes
,
2010,
IEEE Electron Device Letters.
[4]
K. Jefimovs,et al.
Fabrication of all-metal field emitter arrays with controlled apex sizes by molding
,
2009
.
[5]
Jens Gobrecht,et al.
Ultrafast electron emission from metallic nanotip arrays induced by near infrared femtosecond laser pulses
,
2008
.