Alternating-Target Pulsed-Laser Deposition for Tuning Anion Composition of ZrN x H y Epitaxial Thin Films

High Resolution Image Download MS PowerPoint Slide We report on the thin-film growth and electrical properties of ZrN x H y prepared on (0001) α-Al 2 O 3 and (111) MgO substrates by alternating-target pulsed-laser deposition with Zr and ZrN targets in a hydrogen atmosphere. By changing the ratio of the laser pulses used for ablating one to another, x ( y ) was varied from 0.73 (0.03) to 0.05 (1.44). The out-of-plane lattice spacing of the primary phase increased continuously from that of ZrN to that of δ-ZrH 2 as the laser pulse ratio was increased. The secondary phase appeared only in the hydrogen-rich films with y ≥1.23. The Zr–N–H ternary phase diagram verified a widely tunable range of compositions. Temperature-dependent resistivity measurements revealed that the metallicity and superconductivity of ZrN x gradually disappeared upon replacing nitrogen with hydrogen. Moreover, we investigated growth windows for the in-plane epitaxy on (0001) α-Al 2 O 3 and (111) MgO substrates. In the former case, no window was found due to the larger lattice mismatch. In contrast, the in-plane orientation was found to be ZrN x H y [11̅0] || MgO [11̅0] except for the 180°-rotational domains for the samples grown on MgO with a smaller lattice mismatch. The overall results are consistent with the formation of solid solutions, where hydride and nitride ions share interstitial sites in a cubic-closed packing Zr sublattice.