1. Impact of crystallographic facet of InGaN micro-LED sidewalls on electro-optical characteristics.
- Author
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Lex, A., Avramescu, A., Vögl, F., Brandl, M., Binder, M., Hetzl, M., Spende, H., Wolter, S., Waag, A., and von Malm, N.
- Subjects
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INDIUM gallium nitride , *SURFACE passivation , *QUANTUM efficiency , *SURFACE recombination , *SURFACE defects - Abstract
InGaN micro-LEDs (μ LEDs) with their potential high-volume applications have attracted substantial research interest in the past years. In comparison to other III–V semiconductors, InGaN exhibits a reduced susceptibility toward non-radiative surface recombination. However, efficiency degradation becomes more prominent as dimensions shrink to a few μ m or less. Due to the high surface-to-volume ratio of the miniaturized devices, the non-radiative recombination increases and reduces the internal quantum efficiency. While many groups focus on surface passivation to mitigate surface defects, the influence of crystallographic orientation of the μ LED sidewall on the efficiency remains unexplored. This study addresses this gap by investigating the impact of crystallographic orientation of the sidewalls on the emission properties of the μ LEDs. Hexagonal and elongated μ LEDs with dimensions as small as 3.5 μ m and sidewalls with crystallographically well-defined m- and a-planes were fabricated. Electrical and optical properties were investigated using photo- and electroluminescence. External quantum efficiency (EQE) is assessed based on well-known carrier recombination models. It can be shown that μ LED performance intrinsically depends on the crystallographic orientation of the sidewalls. Comparing hexagonal μ LED structures with a-plane and m-plane sidewalls, an increase in the EQE by 33 % was observed for structures with a-plane sidewalls, accompanied by reduction in the current density of the peak EQE by a nearly two orders of magnitude compared to structures with m-plane sidewalls. By analyzing the EQE characteristics at the μ LED center and near the sidewalls, the improvements can be directly attributed to the increased radiative recombination from sidewalls with a-plane orientation. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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