Field-induced hot-electron emission model for wide-band-gap semiconductor nanostructures

摘要

For field emission from wide-band-gap semiconductor nanostructures, nonlinear plots on Fowler-Nordheim (FN) coordinates and unacceptably large field enhancement factors (β_(FN)) are often obtained by fitting based on FN equation. In the present work, the field-induced hot-electron emission model is developed and is found to give theoretical findings consistent with the experimental observation. The hot electrons are produced by heating effect of penetration field into the emitting tip of the nanostructure. This energy is expressed by effective electron temperature T_e, which is much higher than the temperature of bulk structure. By combining the effective electron temperature with thermal emission function and Murphy and Good integration function, the relation between emission current density and external field is derived and the field enhancement factor (β_(Te)) can be calculated quantitatively. For evaluation of the theoretical model, ZnO nanostructure is selected as a concrete example. The results are found to agree with experiment findings. Extremely large field enhancement factor is not needed in our model and nonlinear property of saturation region emerges in nature in our calculation.