Structural change induced in LaAlO3 by ion implantation

Ion implantation is used for various purposes in manufacturing semiconductor devices such as MOS-FETs. In the present study, effects of implantation of P⁺ or B⁺ ions on the structural change of single crystal LaAlO₃ were examined. The optical absorption edge located at about 5.6 eV, which corresponds to the band gap energy of LaAlO₃, is scarcely affected by the ion implantation. The X-ray diffraction peak intensity at 2θ= 23.5° is decreased by the ion implantation. The intensities of three sharp photoluminescence (PL) peaks detected at 1.62, 1.65, and 1.69 eV, which appear only when the samples are crystalline, become smaller by ion implantation. However, the intensity of a broad PL peak at around 2.8 eV due to the oxygen vacancy, which is also detectable in amorphous samples, scarcely changes after the ion implantation. These results indicate that the ion implantation degrades the crystalline LaAlO₃. However, as compared with YAlO₃ with a similar perovskite structure, LaAlO₃ is more resistant to ion implantation.