XPS and optical absorption studies on α-Al2O3 and MgO single crystals implanted with Cr, Cu, and Kr ions

Abstract Charge states of Cu and Cr implanted in α-Al 2 O 3 and MgO were investigated by XPS. Implanted ions are trapped at low concentration of the implants as cations (Cu 2+ and Cr 3+ ), except for Cu ion implantation in α-Al 2 O 3 . It was implied that isolated Cr atoms and a portion of dimers are trapped as Cr 3+ in α-Al 2 O 3 , while isolated atoms, dimers, and trimers are trapped as Cr 3+ in MgO. Optical absorption measurements showed the presence of lattice defects such as F (or F + ) centers, V − centers, and F 2 centers in implanted MgO crystals.