In this paper we use Aimspice device and circuit simulator to demonstrate that uniform current spreading does not only depend on p-transparent metal and n-GaN layers resistivities but is also a strong function of design. This is demonstrated by modeling two light emitting diode (LED) designs, A and B, which differ in the position and size of the p-contact pad. Design A exhibited better Current uniformity than B because of the symmetry in the current spreading length. By keeping the resistivities of p-transparent metal and n-GaN layers fixed, the variation in current uniformity as bias current increases from 20 to 300 mA for design A is only 2%, and similar to9.5%, for design B. The decrease in current spreading uniformity as the resistances of these layers increase is smaller in design A (2-3.5% as resistance increases from 3.8 to 6.7 Omega/square) than design B (9.5-14.5%). A further analysis shows that the Current uniformity increases as the p-transparent metal layer resistance decreases from 25 to 3.8 Omega/square, even though, the n-GaN lateral resistance is fixed at 12 Omega/square. This suggests better uniform current spreading in flipped chip LED design than top-emitting light emitting diodes, since LED flipped chip configuration uses thick reflective metal on top of p-GaN. Further more, current spreading uniformity increases as the thickness of p-transparent metal layer and in this model it peaked at 94.9%,, for a thickness of 15 nm. This is where the contact resistance, which dominates the vertical resistance of the network, had the highest value. It therefore means that the current uniformity is a function of contact resistance, which is based on the thickness of the transparent metal and ultimately affects light extraction. (C) 2003 Elsevier Ltd. All rights reserved.