Abstract
In this work a strategy to grow diamond on β-Ga2O3 has been presented. The ζ-potential of the β-Ga2O3 substrate was measured and it was found to be negative with an isoelectric point at pH ∼ 4.6. The substrates were seeded with mono-dispersed diamond solution for growth of diamond. The seeded substrates were etched when exposed to diamond growth plasma and globules of gallium could be seen on the surface. To overcome problem ∼100 nm of SiO2 and Al2O3 were deposited using atomic layer deposition. The nanodiamond seeded SiO2 layer was effective in protecting the β-Ga2O3 substrate and thin diamond layers could be grown. In contrast Al2O3 layers were damaged when exposed to diamond growth plasma. The thin diamond layers were characterised with scanning electron microscopy and Raman spectroscopy. Raman spectroscopy revealed the diamond layer to be under compressive stress of 1.3–2.8 GPa.
Highlights
In the semiconducting industry silicon is the most widely used material
A solution to the thermal management problem can be to grow a thick diamond layer on b-Ga2O3 single crystal similar to what we have shown in the past on AlN thin films [38]
The determination of the z-potential of a non-diamond substrate, which is directly related to surface charge, is essential for the determination of the type of seed solution needed for high seed density
Summary
In the semiconducting industry silicon is the most widely used material. The band gap of Si is well suited for tailoring the conductivity from semi-insulating to conducting. Based on BFM of different wide band gap materials, b-Ga2O3, AlN, diamond and c-BN are some of the materials that are considered superior to GaN and SiC [5] Of these four materials, b-Ga2O3 has attracted a lot of attention in recent times [5e10], mostly due to availability of large substrates. An alternative approach can be direct bonding of large b-Ga2O3 crystals to chemical mechanical polished [35e37] flat polycrystalline diamond films This technique is not straightforward and will involve non-trivial sample surface preparations. A solution to the thermal management problem can be to grow a thick diamond layer on b-Ga2O3 single crystal similar to what we have shown in the past on AlN thin films [38] Another potential application for direct diamond growth can be formation of ultrawide-bandgap p-n heterojunction. For deposition of thick diamond layers alternative strategies will have to be designed to manage the stress at the interface, which will be the basis of further studies
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