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Hetero-epitaxial growth of LiNbO3 thin film on GaN/Al2O3 by pulsed laser deposition

: Kang, Y.J.; Jeong, S.-Y.; Lee, S.-A.; Hwang, J.-Y.; Kim, J.-P.; Cho, C.-R.

Journal of the Korean Physical Society 49 (2006), Nr.97, S.S625-S628
ISSN: 0374-4884 (Print)
ISSN: 1976-8524 (Online)
Fraunhofer IGB ()

LiNbO3 thin film was deposited on GaN/Al2O3 substrate by the pulsed laser deposition technique. These LiNbO3 films were c-axis oriented and showed pure phase without any secondary phase. An X-ray pole figure shows that LiNbO3 film was epitaxially grown on a GaN/Al2O3 substrate with twin boundaries. The surface roughness of the LiNbO3 film deposited at 750 degrees C was 2.369 nm. The refractive index of the LiNbO3/GaN film was determined by using a variable-angle spectroscopic ellipsometer. Films deposited at low substrate temperatures had a refractive index (n similar to 2.12) similar to that of bulk crystal. The relative dielectric constant of all films was smaller than that of a bulk sample, but the crystallinity and refractive index were slightly changed with varying substrate temperatures. We suggest that epitaxial LiNbO3 film on a GaN substrate is useful for designing electro-optical devices such as modulators and deflectors integrated with GaN-based laser diodes and photodetectors.