Influences of graded superlattice on the electrostatic discharge characteristics of green InGaN/GaN light-emitting diodes

In this paper, the influence of a Si-doped graded superlattice (SiGSL) on the electrostatic discharge (ESD) characteristics of green InGaN/GaN light-emitting diodes (LEDs) is discussed. To investigate the effects of Si doping to the superlattice, green LEDs were also fabricated on undoped graded superlattice (unGSL). Furthermore, a conventional green InGaN/GaN LED without the superlattice (C-LED), emitting at a wavelength of 534 nm, was also prepared as a reference. The current-voltage (I-V) curves for the C-LED and the unGSL-LED subjected to the ESD treatments at surge voltages from 2000 to 8000 V showed a drastic increase in the leakage current. However, there was relatively small change in the I-V curves for the SiGSL-LED after the ESD treatments, even at the surge voltages of 6000 and 8000 V. After the ESD treatment at a surge voltage of 8000 V, the EL intensities for the C-LED, unGSL, and SiGSL, measured at a driving current of 120 mA, were reduced by 55, 53, and 30%, respectively, compared to those of the as-fabricated LEDs.