Epitaxial Growth on 150 mm 2° off Wafers

In this work a new epitaxial process on 6 inches has been performed on 2° off-cut substrate. This off-cut will reduce the material loss during substrate preparation from the crystal boule. The thickness and doping uniformity of the samples grown in the LPE reactor PE1O6 is extremely good and the PL map shows a low defects density. The roughness is slightly higher on 2° off-cut and the process window becomes narrower.

Electromechanical Properties and Microstructure of Undoped K0.5Na0.5NbO3 Ceramics and KNbO3-NaNbO3 Crystals

K0.5Na0.5NbO3(KNN) was manufactured by spark plasma sintering (SPS), which is a fast sintering method allowing to control the grain growth. Different samples of KNN are sintered with SPS at 920°C under 50 MPa for 5 minutes. High densities over than 97% are achieved. In order to make domain engineering, KNN crystals are grown by floating zone method. Stable molten zone is reached when oxygen or nitrogen gas flux is used, leading up to 50 mm length of crystals. High electromechanical coupling factor kt about 46 %, kp around 45 % and ε33S/ε0 of 253 are achieved for KNN ceramics poled at optimum electric field about 3 kV / mm. KNN crystal boule exhibits kt about 40 % against 34 % for KNN ceramic, both poled at 1 kV / mm. These results are promising to replace PZT for transducers applications.