Investigation of electrical properties of InGaN based micro light emitting diode (µLED) arrays achieved by direct epitaxy

A systematic study has been carried out on a series of InGaN based micro-LED (µLED) array samples which were achieved using our direct epitaxy overgrown approach on patterned templates by metalorganic chemical vapour deposition technique, where the diameters of the µLEDs are 40 μm, 5 μm and 3.6 μm, respectively. Our selective epitaxy approach allows us to circumvent the major limitations of conventional fabrication methods of µLEDs which unavoidably introduce dry-etching induced damages. Electrical characterisations have been performed on our selective epitaxy overgrown µLEDs as well as conventional µLEDs fabricated using a standard dry-etching method. For our overgrown µLEDs, the leakage current per µLED is smaller than those of the conventionally mesa-etched µLEDs. It is worth highlighting that our single 3.6 µm µLED exhibits as low as a leakage current of 14.1 nA at a bias of -5 V. Moreover, in terms of leakage current density, our overgrown µLEDs exhibit much smaller and more consistent leakage than their mesa-etched counterparts. Operational voltage RC constants also show more favourable to our overgrown devices than the conventionally mesa-etched µLEDs.