Effect of laser repetition rate on the growth of Sc 2 O 3 via pulsed laser deposition

This paper reports a study of the effect of laser pulse repetition rate and substrate temperature on the properties of crystalline Sc 2 O 3 films grown on <0001>-oriented sapphire via pulsed laser deposition (PLD). For the range of substrate laser-heating powers investigated, optimum <111>-film growth was obtained at the highest available repetition rate of 100 Hz. Scanning electron microscopy and X-ray diffraction measurements revealed that a decrease in the repetition rate favours highly textured/island growth. The repetition rate was also proven to affect the lattice constant of the films, with a difference up to 0.3% between the films grown at high and low repetition rates. The general trend indicates that the out-of-plane lattice constant of the film shifts closer to the bulk value when the pulse repetition rate is increased. However, the lattice constant could also be reduced through in-situ post-growth annealing, which had the additional benefit of reducing the width of the (222) rocking curve peak. This work provides further evidence that energetic-PLD dynamics leads to higher quality PLD-grown crystalline films and for this material undermines the old adage that lower pulse repetition rates lead to higher quality thin-film crystalline growth.