Growth of c-plane ZnO on γ-LiAlO2 (1 0 0) substrate with a GaN buffer layer by plasma assisted molecular beam epitaxy

Highlights

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ZnO epilayers were grown on LiAlO₂ (1 0 0) substrate with a GaN buffer layer by MBE.

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A high Zn/O flux ratio is beneficial for reducing the density of screw dislocations.

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Reciprocal space maps demonstrate that the misfit strain in ZnO has been relaxed.

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No interfacial layer is formed at ZnO/GaN interface using a Zn pre-exposure strategy.

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C-plane ZnO epilayers were grown on LiAlO₂ (1 0 0) substrate with a GaN buffer layer by plasma assisted molecular beam epitaxy. Both the X-ray rocking curves and the transmission electron microscopy analyses indicate that the ZnO epilayers exhibit a lower threading dislocation density (∼1 × 10¹⁰ cm⁻²) as compared to those grown on LiAlO₂substrate without the buffer layer. A high Zn/O flux ratio is beneficial for reducing the density of screw-type dislocations. Reciprocal space maps demonstrate that the misfit strain has been relaxed. No interfacial layer is formed at the ZnO/GaN interface by using a Zn pre-exposure strategy. The ZnO epilayers exhibit a strong near band edge emission at 3.28 eV at room temperature with a negligible green band emission.

Keywords

• A3. Molecular beam epitaxy; 
• A3. Buffer layer; 
• B1. ZnO; 
• B1. LiAlO₂; 
• B1. GaN
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    • Source:Sciencedirect 
      
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