Effect of the Electrode Pattern on Current Spreading and Driving Voltage in a GaN∕Sapphire LED Chip

Abstract

The effects of p-and n-electrode patterning on the current spreading and driving voltage of a side-view GaN/sapphire lightemitting diode ͑LED͒ chip are investigated via a numerical simulation. The numerical results ͑current distributions͒ for the striped pattern p-electrode are well consistent with the optical emission patterns taken from emission images. A desirable uniformity of the current distribution in the active layer can be obtained by the appropriate arrangement of p-and n-electrode patterns. At the same time, a lower voltage drop in the LED chip is also obtained due to a more uniform current distribution in the p-GaN layer and a smaller overall distance for current movement in the n-GaN layer. With an injection current of 30 mA, a decrease in driving voltage of 13% for well-designed electrode patterns can achieve compared to the control devices considered in this study.

A Numerical Model for Studying Multimicrochip and Single-Chip LEDs With an Interdigitated Mesa Geometry

“…In addition, the superior heat dissipation and better current spreading of the LED make it able to operate under higher power conditions. There are some methods to increase the light output of a LED chip, e.g., to design a better electrode pattern for a single LED chip [1], [3]- [6] and to manufacture a monolithic LED chip array [7], [8]. When the input power of a LED chip is enlarged, it results in an increase in the current and heat crowding.…”

“…When the input power of a LED chip is enlarged, it results in an increase in the current and heat crowding. Therefore, some methods have been developed to improve the current spreading and heat transfer in LED chips by means of the optimum design of the electrode pattern and the geometry of the epitaxial structure [3]- [6]. Chakraborty et al [7] fabricated an interdigitated multipixel array (IMPA) chip, which can suppress the current crowding and thereby improve the LED performance at high current injection.…”

“…Hwang et al [32] developed a 3-D numerical simulation model incorporating the concept of series and parallel connections to investigate the current spreading in a LED. Recently, the finite-element scheme has been utilized to compute the electric potential and current density distribution in the LED chip directly, through the continuity equation of electronic transport [6], [33]. With this approach, the simulation of complex LED structures becomes possible.…”

“…They compared the numerical results with the experimental results obtained by Chakraborty et al [7] and obtained a good agreement in the output optical power but had some errors in current-voltage (I-V ) characteristics. Hwu et al [42] extended the numerical model proposed by Chen and his coworkers [6], [33] to include the thermal effect. A simulation was performed for vertical LED chips with different n-electrode areas taking into account the effect of current blocking layer size.…”

Improvement of GaN light-emitting diodes with surface-treated Al-doped ZnO transparent Ohmic contacts by holographic photonic crystal

“…Recently, high-efficiency GaN-based light-emitting diodes (LEDs) attracted considerable interest due to their potential applications in optoelectronic devices such as traffic signals, full-color displays, and high efficiency lamps [1][2][3][4]. Improved LED performances through enhanced light extraction have been reported and commercialized using transparent conducting oxide (TCO) contacts with optical output comparable or superior to conventional LED [5,6], such as impurity doped SnO 2 , In 2 O 3 , and ZnO, etc.…”