NiO thin film with an extremely high index $$(7 \overline{1 } 4)$$ on r-plane sapphire substrate

Abstract

AbstractThin film epitaxy is essential for state-of-the-art semiconductor applications. The combination of different substrates and deposition methods leads to various crystallographic orientation relationships between thin films and substrates, which have a decisive impact on thin film performance. By utilizing pulsed laser deposition, we discovered a very high-index $$(7 \overline{1 } 4)$$ ( 7 1 ¯ 4 ) –oriented NiO thin film when deposited on r-plane $$\text{(10}\overline{1}\text{2)}$$ (10 1 ¯ 2) sapphire substrates. The in-plane epitaxial relations are $${[13\overline{1 }]}_{\text{NiO}}\text{||[1}\overline {2}{\text{10]}}_{\text{Sapphire}}$$ [ 13 1 ¯ ] NiO ||[1 2 ¯ 10] Sapphire and $${[\overline{1 }12]}_{\text{NiO}}\text{||[10}\overline{11}{\text{]}}_{\text{Sapphire}}$$ [ 1 ¯ 12 ] NiO ||[10 11 ¯ ] Sapphire , and the lattice mismatch is 3.2% and 0.4% along two directions, respectively. Exchange bias studies by the deposition of Co on NiO (111) and NiO $$(7 \overline{1 } 4)$$ ( 7 1 ¯ 4 ) show different behaviors, which may be associated with the spin density and alignment on the surface. Graphical abstract