Characteristics of GaN-Based High-Voltage LEDs Compared to Traditional High Power LEDs

In this letter, GaN-based high-voltage light-emitting diodes (HV-LEDs) arrays with 16 microchips connected in series are fabricated. The light output power-current-voltage (LOP-I-V) characteristic of HV-LEDs is measured. Under input power of 1.1 W, the LOP of HV-LEDs is enhanced by 11.9% compared to traditional high power light-emitting diodes (THP-LEDs) with the same chip size. Due to the reduced metal shadow effect and better current spread, the HV-LEDs exhibit higher light extraction efficiency under the same current density, which is simulated by a 3-D ray tracing method. As a result, the luminous efficiency of HV-LEDs is 21.6% higher than that of THP-LEDs under input power of 1.1 W. Furthermore, the efficiency droop of HV-LEDs is reduced to half of that of THP-LEDs.