Surface zeta potential and diamond growth on gallium oxide single crystal

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.