Electron field emission from wide band-gap semiconductors (GaN)

In order to explain the obtained experimental results on electron field emission from nanostructured surfaces of GaN, a model was proposed taking into account the changing of carrier concentration distribution in the main and the satellite valley during the emission process. The lowering of work function (due to the increased number of carriers in the satellite valley) can explain the decrease of the F-N plot slope. In case of n-type doped GaN the lowering of work function can be caused by electron transition from the main valley (Gamma) to upper satellite valley (X) due to the heating in high electric fields. The nanostructured surfaces of GaN have nanometer tip diameter (d<10 nm). Under such circumstances the quantum size confinement effect causes the energy band reconstruction. It was shown that the energy difference between the main and satellite valley in GaN was decreased in case of quantum confinement, thus increasing the probability of electron transition from Gamma to X valley at same electric fields.