Abstract
The fie Id emr,ssion current *from n- type GaN is theore tical& obtained by calculatrng the contrrbiitron from the hidk .state. only. By solving the Porsson eqiiatron .for given alyl~ed~fields, we calculate the hand prc?file with the hand bending at the surface. It IS afomd that the eniissron current J increases with increasing doping density n. Such n-dependence is obtained !f the internal voltage drop in the senzicondi.jcfor IS taken into account. The .J 1.5' also calcidated .for several electron affinities x. It is also jbiind that .for the reported values of x, the emission ci.jrrenf j?om a planar electrode can not describe the measured I-V curve. !fa Taylor-cone tip IS assumed to he a hexagonal pyramid emitter, the field intensify F around the cone aIxx IS strong enough to yield J in agreement with experiment. However, such a strong value of F may he close to the breakdown ,field Gallium nitride is a wide bandgap semiconductor which has a broad range of applications for combined optoelectronic and electronic devices. Owing to mechanical hardness, low electron affinity, and high electron carrier concentration, GaN is highly promising for use in practical field emission devices. Recently, the electron field emission from GaN has been observed for the first time by Underwood et al.[ I] They obtained the emission current of 0.8 pA at 2000 V from GaN hexagonal pyramid emitter arrays with the anode being 0.5 mm above. No theoretical calculations have been reported yet. In the present work, we calculate the field emission current from the n-type wurzite GaN along (0001) direction. We assume an independent electron model with the current flow only in the z direction. The current density of emitted electrons from a particular electron energy band is then given by the following equation.
Published Version
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