Substrate dependence of the crystallinity and mosaic texture of YBa₂Cu₃O_7−δ ultrathin films deposited by laser ablation

C-axis oriented ultrathin films with good crystallinity were deposited by laser ablation on both SrTiO 3 null and NdGaO 3 null substrates. The full width at the half maximum of the rocking curves of the (005) peak δω of our ultrathin films with thickness null d null ≤ 150 A is less than 0.11°, and the χ min null of the 150 A films on SrTiO 3 null determined by RBS is equal to 8.5%. SrTiO 3 null and NdGaO 3 null have different degrees of lattice...