Theoretical considerations on current spreading in GaN-based light emitting diodes fabricated with top-emission geometry

We report theoretical considerations regarding current spreading in GaN-based light emitting diodes (LEDs) fabricated with top-emission geometry, in which sheet resistances of both top transparent electrodes and n-layers are taken into consideration, whereas vertical resistance associated with the p-contact and the p-layer is neglected. The current spreading length (L _s) is inversely proportional to the injected current density (J ₀), namely, L_s J₀^-1/2, and can be increased as the sheet resistances of either the transparent electrode or the n-layer are reduced. The effects of the material parameters (sheet resistances of transparent electrode and n-layer) on current spreading and hence the LED performance are discussed.