Characterizations of ZnO/Ga2O3 superlattices grown by atomic layer deposition.
POSTER
Abstract
We have studied the structural and optical properties of ZnO/Ga2O3 superlattices (SLS) grown by ALD on (0001)-Al2O3, (100)- and (111)-Si substrates. Samples were grown followed the ratio of ALD cycles for ZnO (m) to Ga2O3 (n) was fixed at m:n $=$ 2:3, while total thickness is the same for all. The structural properties used XRD and TEM indicate that samples are polycrystalline, while XRR confirmed the presence of SLS structures, albeit with rough interfaces suggesting that epitaxial growth in this system involves complex reaction kinetics. RTPL investigated relevant levels of energy transitions. For the thicker ZnO and Ga2O3 layers we observed a strong band emission peak at 3.36 eV, close to the bandgap of bulk value 3.37 eV. As the ZnO and Ga2O3 thicknesses were reduced, the band emission peak also reduced drastically. The causes behind the optical properties are further discussed in association with the first-principles calculations.