Characterization of the internal properties of InGaN/GaN core–shell LEDs (Phys. Status Solidi A 1∕2016)

Abstract

The front cover shows an SEM image (view field = 9 μm) visualizing the light emitting region of a cleaved InGaN/GaN core-shell micro-LED pillar which was selectively grown on a sapphire substrate. The cleaved pillar is contacted by two probe tips (colorized in green) while obtaining the EBIC (red) and SE (cyan) images at a substrate tilt of 30°. This electrical characterization by means of EBIC imaging is giving proof of the presence of a depletion region as well as the intended doping polarity of the n-type core and a p-type shell wrapped around the whole structure with an aspect ratio of about 2.5. Such an array of three-dimensional LEDs is supposed to have substantial advantages over their conventional planar LED counterparts. In particular the light emitting area and hence the light output will drastically be enhanced as its active area per substrate area is scaling with the aspect ratio of the LED pillar. In the corresponding article (pp. 11–18), Johannes Ledig et al. present the structural, optical, and electrical characterization of these structures.