[摘要]：The enhancement of electron field emission efficiency due to illumination by low energy photons has been investigated. Illumination of electron field emitting GaN cathodes with light energy lower than the bandgap caused an increase of the emission current and a change in the slope of the emission curves as evidenced by Fowler-Nordheim characteristics. The observed properties suggest a change of effective emission barrier due to charge carrier excitation. The influence of light modulation on the field emission current was also investigated with an increase of emission current only observed at lower light modulation frequencies. Two slopes were observed in the Fowler-Nordheim curves without illumination; namely, a larger slope at lower voltages and a smaller slope at higher voltages. Such behavior has been explained by emission from the Gamma- and X-valley, respectively. Key field-emission parameters were determined from the Fowler-Nordheim plots and are reported. Another important peculiarity is the relative decrease of the ratio of illuminated to dark current under maximum voltage operation conditions. (C) 2012 American Vacuum Society. [http://dx.doi.org/10.1116/1.3692253]
