Surface recombinations in III-nitride micro-LEDs probed by photon-correlation cathodoluminescence

Sylvain Finot (1) , Corentin Le Maoult (2) , Etienne Gheeraert (1) , David Vaufrey (2) , Gwenolé Jacopin (1)

1 NEEL - SC2G - Semi-conducteurs à large bande interdite
2 CEA-LETI - Commissariat à l'énergie atomique et aux énergies alternatives - Laboratoire d'Electronique et de Technologie de l'Information

III-nitride micro-LEDs are promising building blocks for the next generation of high performance micro-displays. To reach a high pixel density, it is desired to achieve micro-LEDs with lateral dimensions below 10 µm. With such pixel downscaling, sidewall effects are becoming important and an understanding of the impact of non-radiative surface recombinations is of vital importance. It is thus required to develop an adapted metric to evaluate the impact of these surface recombinations with a nanoscale spatial resolution. Here, we propose a methodology to quantitatively assess the influence of surface recombinations on the optical properties of InGaN/GaN quantum wells based on spatially-resolved time-correlated cathodoluminescence spectroscopy. By coupling this technique to a simple diffusion model, we confirm that the combination of KOH treatment and Al$_2$O$_3$ passivation layer drastically reduces surface recombinations. These findings emphasize the need for nanoscale time-resolved experiments to quantify the local changes in internal quantum efficiency of micro-devices.

Mots clés: light-emitting diodes; surface recombination; carrier dynamics; III-nitride; cathodoluminescence; diffusion

Domaines: Optique / photonique; Electronique

Sylvain Finot, Corentin Le Maoult, Etienne Gheeraert, David Vaufrey, Gwenolé Jacopin. Surface recombinations in III-nitride micro-LEDs probed by photon-correlation cathodoluminescence. ACS photonics, 2021, 9 (1), pp.173-178. ⟨10.1021/acsphotonics.1c01339⟩. ⟨hal-03469521⟩