Spatially resolved field emission measurements represent an important factor in further development of existing field emitter concepts. In this work, we present a novel approach that allows quantitative analysis of individual emission spots from integral current-voltage measurements using a low-cost and commercially available CMOS camera. By combining different exposure times to extrapolate oversaturated and underexposed pixels, a near congruence of integral current and image brightness is shown. The extrapolation also allows parallel investigation of all individual tips participating in the total current with currents ranging from a few nanoampere to one microampere per tip. The sensitivity, which is determined by the integral brightness-to-current ratio, remains unchanged within the measurement accuracy even after ten full measurement cycles. Using a point detection algorithm, the proportional current load of each individual tip of the field emitter array is analyzed and compared at different times during the initial measurement cycle. Together with the extracted I–V curves of single emission spots from the integral measurement, the results indicate the effect of premature burnout of particularly sharp tips during conditioning of the emitter.

In the present work, black-silicon field emitter arrays (FEAs) are investigated regarding the influence of residual gas pressure on the characteristics and lifetime in the high voltage triode setup. Current-voltage-characteristics at different pressure levels are recorded and show a decreasing emission current with rising pressure. This decrease can be explained by an increase of the work function and charging of the emitter surface caused by adsorbates. The emission current can be restored to its initial value by heating of the FEA up to 110 °C during active emission. With this regeneration procedure, an extended lifetime from about 20 h to 440 h at a residual gas pressure of 10−5 mbar is achieved.

A compact vacuum-sealed field emission electron gun with an operation voltage below 5 kV is presented. With a 150 nm thick pyrolytic carbon membrane, a transmission of 40% at 5 kV is obtained. For more than 2500 h of continuous operation at an emission current of 100 nA, no significant increase (<50V) and almost no degradation were found. From this measurement, a lifetime of more than 10 000 h at continuous operation with approximately a linear increase of the extraction voltage from about 545 V to about 730 V is predicted. This electron source enables application of field emitter arrays in poor vacuum or even ambient pressure.

Using p-type semiconductors for field emitters is one simple way to realize an integrated current limiter to improve the lifetime of the cathode. In this work, the origin of the current saturation of p-type silicon emitters is investigated in detail. Single emitters are electrically characterized and compared to simulation results. With a simulation model considering a high surface generation rate and elevated tip temperature, a good agreement to the measured data is found. This observation is supported further by alteration of the surface experimentally. Electrical measurements after different treatments in hydrofluoric acid as well as heated and subsequent operation at room temperature are well explained by the influence of surface generation. Furthermore, it is shown that the field penetration leads to a small voltage drop and a strong geometry-dependent reduction of the field enhancement factor.

Silicon field emitter arrays (FEAs) with different tip sizes and quantities were fabricated by saw dicing and anisotropic wet chemical etching by tetramethylammonium hydroxide. The tip is formed by the different etching rates of the crystal facets leading to a sharp pyramid based on {103} planes on the top and a hexadecagon based on {331} and {221} planes on the bottom. Electrical measurements at 10−5 mbar up to 10 μA show good reproducibility for FEAs with the same process parameters and higher uniformity and stability with an increasing number of tips. Constant current measurements at the same conditions and 10 μA show a mean electric field increase of about 0.06(3) V/(μm h) for p-type FEAs with a tip quantity of 3600. The shift increases with lower tip quantity and is higher for n-type FEAs compared to p-type. The degradation during the constant current measurement of n-type samples is found to be partly reversible by heating to 200 °C during emission. In contrast, heating of p-type FEAs induced further degradation instead of a regeneration effect.