Maximizing the notional area in single tip field emitters

One of the critical aspects in advancing high-brightness field emitter devices is determining the conditions under which single-tip emitters should be constructed to optimize their emission area. Recent experiments have explored varying the axis ratio ξ of the cap of a single-tip emitter, ranging from an oblate semi-spheroid to a prolate shape, mounted on a nearly cylindrical conducting body. In this work, we present a strategy, based on high-accuracy computer simulations using the finite element technique, to maximize the emission area of those single-tip emitters. Importantly, our findings indicate that the notional emission area achieves its maximum when the emitter’s cap is adjusted to an oblate semi-spheroid with a characteristic axis ratio ξC≈0.85. We do a comparison of notional emission area as a function of ξ for an ellipsoidal emitter on a post and compare these results from other emitter configurations, which are feasible to fabricate. •A more distributed electron emission enhances luminosity and prevents hot spots and emitter degradation.•Rounded ends on single tip field emitters with a cylindrical post can maximize the notional emission area.•The notional emission area peaks when the emitter’s cap is an oblate spheroid with an axis ratio of about 0.85.•The emitter’s cap axis ratio for maximum emission area is constant from 1 nA to 100 μ A.•Our results pave a way to improve tips for electron emission in high-resolution microscopy.