Incongruent transfer related to surface segregation in pulsed-laser-deposited La–Ca–Mn–O films

A range of La–Ca–Mn–O films have been grown using pulsed-laser deposition on hot Si substrates. The composition of the films is found to be strongly dependent on substrate temperature (Ts) with the calcium and oxygen content being significantly reduced at high Ts (>700 °C). The kinetic energies of the various ions in the laser generated plume are found to be distributed in the 10–100 eV range, high enough to induce resputtering from deposited films. Surface segregation was also observed in the films grown at high Ts (>700 °C), resulting in a Ca-rich surface. Preferential resputtering of these surface Ca-rich segregated samples, driven by a mixture of high energy ion irradiation and thermally activated processes, is proposed to explain the observed phenomena.