A non-uniform current spreading in the current spreader can greatly reduce the efficiency of the light-emitting diode (LED). The effects of the electrode contact area to the spreading layer towards extraction efficiency of LED chips is analysed in analytical simulations. Length of current spreading and light extraction efficiency is analysed for variation of contact area. The contact area value is varied by changing the shape of the electrode and the value of width of contact area. The increase in contact area decreases light extraction efficiency as more light are absorbed by the bottom electrode surface. The effective current spreading length for Indium Tin Oxide (ITO) of thickness 300nm is 36.44µm. The 6 strips ‘fork’ design is the most optimum. The design has the most area for photons produced in active region to escape without reducing the area cover with current density. This enables the chip to has more extraction efficiency with more uniform current spreading.
Suppression of “volcano” morphology and parasitic defect luminescence in AlGaN-based deep-UV light-emitting diode epitaxy