Heterogeneous integration of thick GaN and polycrystalline diamond

 

Heterogeneous integration of thick GaN and polycrystalline diamond

Direct heterogeneous integration of GaN on diamond will improve devices performance and reliability for high-power applications, however it is challenging to integrate thick GaN films and polycrystalline diamond (p-diamond) substrates.

Recently a dynamic plasma polishing (DPP) technique was adopted on the diamond to flatten surficial spikes from maximum 15 nm to 1.2 nm, obtaining a smooth surface with 0.29 nm Ra, achieving a robust GaN/diamond bonding with high bonding rate of ∼92% at room temperature combining the surface-activated bonding (SAB) method. The chemical status, thermal stress, and interfacial microstructures of GaN/diamond heterostructures were analyzed, revealing a residual stress of ∼200 MPa at the GaN/diamond interface, and the asymmetric increase of interfacial stress at rising temperature demonstrates the effectiveness of amorphous interlayer to release the stress.

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