Abstract
We investigated the modulation responses and optoelectronic properties of light-emitting diodes (LEDs) grown on free-standing (0001) GaN. These LEDs have a larger modulation bandwidth than those grown on sapphire at a higher current density, and a maximum of -3 dB modulation bandwidth of 510 MHz was achieved, which is 1.7 times larger compared to LEDs grown on sapphire. In addition, due to the lower substrate temperature, there may be an increase in the indium that is incorporated into the active region as well as the point defects of the LEDs grown on GaN, which will influence the optoelectronic properties. (C) 2018 The Japan Society of Applied Physics