A Novel GaN LED Structure With Both P and N Discontinuous Ohmic Contacts and Discontinuous CBL

Abstract

In this paper, a novel kind of GaN light-emitting diode (LED) with P and N discontinuous ohmic contact electrodes and discontinuous current blocking layer (CBL) is designed and prepared. Multiple contact windows under the N- and P-electrodes formed by etching help realize the discontinuous ohmic contacts with the N-GaN layer and the ITO layer, respectively. Similarly, by etching a plurality of discontinuous openings with the same pitch in the CBL, a discontinuous CBL structure is formed. As compared with traditional structures, the discontinuous ohmic contacts can maximize the number of current paths which allow the carriers to be collected from all four directions, leading to a more uniform current spreading and thermal management. Furthermore, as the contacts are not continuous any longer, some of the otherwise removed materials (such as the active region) lying between the patches are saved. The optoelectronic characteristics, junction temperature, thermal resistance, and infrared thermography measurements are conducted and the current distribution is simulated. The results show that the novel LED structure has better optoelectronic performances and current spreading ability compared to traditional devices. At 150 mA current, the luminous efficiency is 15.2% higher than the traditional LED, the junction temperature is reduced by 4.9%, and the thermal resistance is reduced by 12%.

Keywords

• GaN LEDs
• discontinuous ohmic contact electrodes
• current spreading
• thermal management