WINDOW LAYER FOR CURRENT SPREADING IN ALGAINP LIGHT-EMITTING DIODE

The current spreading effect and other characteristics of an AlGaInP d ouble-heterojunction (DH) light-emitting diode (LED) were investigated via numerical calculation and experimental results. The finite differ ence method was employed to numerically solve the two-dimensional stea dy-state equations of a semiconductor device. Poisson's equation and t wo continuity equations were approximated by a set of equations under the assumption that the hole and electron current components along the mesh lines are constant between two neighboring mesh points. Addition ally, the DH structure was modified to a simple p-n junction model, in light of the fact that the former does not contribute significantly t o the current spreading effect. Furthermore, a comparison of the measu red light intensities from LEDs with the calculated current densities revealed a sufficient correlation. Experimental results indicated that a 10-mum-thick window layer with a carrier concentration at 2 X 10(18 ) cm-3 would be adequate for an optimum device.