The growth of purely a-axis oriented YBCO thin films on LaAlO3 (100) s
ubstrates with no template layer addition has been accomplished by pho
to-assisted MOCVD. In addition to the requirement of lattice-matched s
ubstrates, the difficulty of growth of purely a-axis oriented YBCO fil
ms with this processing technique has been overcome by utilizing three
appropriate processing/growth factors: substrate temperature (T-s), t
otal partial pressure of oxidizing gases O-2 and N2O (P(O-2 + N2O)), a
s well as high film growth rate. A high growth rate (up to 7000 Angstr
om/min) has been accomplished through MOCVD growth assisted by photo-i
rradiation with tungsten-halogen lamps. Variance of the three factors
leads to tailored growth of either a-axis, c-axis or [110] oriented gr
owth for YBCO. The growth of a-axis YBCO thin films under different pr
ecursor flow rates also affects the film morphology.