Highly c-oriented LiNbO3 films on polycrystalline diamond substrate for high frequency surface acoustic wave devices

摘要

Highly c-oriented LiNbO3 films were deposited on aluminum oxide (Al2O3) buffered diamond substrates by a novel two-step pulsed laser deposition. The two-step growth method (growth at 500 mTorr oxygen partial pressure for 15s followed by 12 min growth at 100 mTorr oxygen pressure) greatly enhanced the c-oriented LiNbO3 film crystallinity and improved the film surface flatness. The Al2O3 buffer layer was shown to be able to protect the diamond surface from oxidation during LiNbO3 film growth under high oxygen pressure and also favorable for c-oriented LiNbO3 film growth. By utilizing such a stacked structure of LiNbO3/Al2O3/diamond, surface acoustic wave devices were fabricated and characterized.