High‐Brightness Blue Light‐Emitting Diodes Enabled by a Directly Grown Graphene Buffer Layer
Single‐crystalline GaN‐based light‐emitting diodes (LEDs) with high efficiency and long lifetime are the most promising solid‐state lighting source compared with conventional incandescent and fluorescent lamps. However, the lattice and thermal mismatch between GaN and sapphire substrate always induc...
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Veröffentlicht in: | Advanced materials (Weinheim) 2018-07, Vol.30 (30), p.e1801608-n/a |
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Sprache: | eng |
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Zusammenfassung: | Single‐crystalline GaN‐based light‐emitting diodes (LEDs) with high efficiency and long lifetime are the most promising solid‐state lighting source compared with conventional incandescent and fluorescent lamps. However, the lattice and thermal mismatch between GaN and sapphire substrate always induces high stress and high density of dislocations and thus degrades the performance of LEDs. Here, the growth of high‐quality GaN with low stress and a low density of dislocations on graphene (Gr) buffered sapphire substrate is reported for high‐brightness blue LEDs. Gr films are directly grown on sapphire substrate to avoid the tedious transfer process and GaN is grown by metal–organic chemical vapor deposition (MOCVD). The introduced Gr buffer layer greatly releases biaxial stress and reduces the density of dislocations in GaN film and InxGa1−xN/GaN multiple quantum well structures. The as‐fabricated LED devices therefore deliver much higher light output power compared to that on a bare sapphire substrate, which even outperforms the mature process derived counterpart. The GaN growth on Gr buffered sapphire only requires one‐step growth, which largely shortens the MOCVD growth time. This facile strategy may pave a new way for applications of Gr films and bring several disruptive technologies for epitaxial growth of GaN film and its applications in high‐brightness LEDs.
A high‐quality GaN layer is directly grown on chemical‐vapor‐deposition‐derived graphene/sapphire substrate. The graphene/sapphire substrate greatly releases biaxial stress in the GaN film, leading to a reduction of the dislocation density. The thus‐obtained GaN film enables much higher light output power of as‐fabricated light‐emitting diode devices which brings several disruptive technologies for III‐nitride epitaxy growth and graphene applications. |
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ISSN: | 0935-9648 1521-4095 |
DOI: | 10.1002/adma.201801608 |