(Color online) Cross sectional diagram of a 90° hop funnel.
(Color online) Photograph of 60° hop funnels that were constructed out of LTCC for this work. Half of the funnels have a metal layer on the hop bottom and half have no metal bottom.
(Color online) Experimental setup showing the anode, field emission array, hop funnel, and configuration of bias voltages. The inset shows an exploded view providing the pictorial representation of the field emitters.
(Color online) I–V curve behavior that was most commonly seen with the 60° funnels where (a) and (b) are funnels without a metal bottom and (c) and (d) have a metal hop bottom. The curves show a relatively consistent form with sharp transitions on the ramp up and ramp down; however, the voltage at which this transition occurs is not consistent. Note that ramp up has a higher transition voltage than the ramp down.
(Color online) I–V curve behavior that was most commonly seen with the 90° funnels where (a) and (b) are two curves obtained from funnels without a metal bottom and (c) and (d) are two curves obtained from funnels with a metal hop bottom. A more linear behavior was seen with these funnels but was not always the case. Note that ramp down has a higher transition voltage than the ramp up, which is opposite from the results observed with the 60° funnels.
(Color online) I–V curves showing additional results that were observed. (a) is a 90° funnel with a metal bottom; notice that the funnel reaches unity gain at a much lower voltage than common results shown in Fig. 4 ; (b) shows a 90° funnel without a metal bottom; this specific case showed more of a knee type behavior that was more common in the 60° funnels. Also, the ramp down has a lower transition voltage than the ramp up. The I–V curve shown in (a) was conducted using a PixTech cathode, whereas (b) was conducted using a Motorola cathode.
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