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Gallium nitride; Graphite electrodes; III-V semiconductors; Light emitting diodes; Optical properties; Plasma CVD; Plasma enhanced chemical vapor deposition; Substrates; Transparent electrodes, Current spreading effect; Electrooptical properties; GaN-based light-emitting diodes; Graphene electrodes; Graphene layers; Plasma enhanced chemical vapor depositions (PE CVD); Target-substrate; Transfer process, Graphene
Abstract:
One of the bottlenecks in the implementation of graphene as a transparent electrode in modern opto-electronic devices is the need for complicated and damaging transfer processes of high-quality graphene sheets onto the desired target substrates. Here, we study the direct, plasma-enhanced chemical vapor deposition (PECVD) growth of graphene on GaN-based light-emitting diodes (LEDs). By replacing the commonly used hydrogen (H2) process gas with nitrogen (N2), we were able to suppress GaN surface decomposition while simultaneously enabling graphene deposition at lt;800 °C in a single-step growth process. Optimizing the methane (CH4) flow and varying the growth time between 0.5 h and 8 h, the electro-optical properties of the graphene layers could be tuned to sheet resistances as low as ∼1 kΩ/D with a maximum transparency loss of ∼12. The resulting high-quality graphene electrodes show an enhanced current spreading effect and an increase of the emission area by a factor of ∼8 in operating LEDs. © 2020 The Author(s).
