High-Frequency Modulation of GaAs/AlGaAs LEDs Using Ga-Doped ZnO Current Spreading Layers

In this letter, we report the high-frequency modulation of GaAs/AlGaAs near-infrared (NIR) light-emitting diodes (LEDs) with gallium-doped zinc oxide (GZO) prepared by atomic layer deposition as a current spreading layer. This report analyzes the effects of aperture area of the NIR LEDs on minority carrier lifetime and further investigates the required injection current to achieve the 3-dB frequency bandwidth of 100 MHz. At the same injection current density, the LEDs with different aperture areas always exhibit the same minority carrier lifetime, which is inversely proportional to the square root of current density. It means that the GZO layer plays a good current spreading in the lateral direction from the ohmic contact of NIR LEDs, which shows the lower contact resistance and lower forward voltage.