XPS studies on the charge states of Cr and Cu atoms implanted into α-Al2O3 and MgO single crystals

Abstract The charge state of Cr and Cu atoms implanted into α-Al 2 O 3 and MgO single crystals has been studied by X-ray photoelectron spectroscopy (XPS). The implantation has been performed at 200 and 300 keV to doses of 10 16 to 10 18 /cm 2 . The implanted Cr atoms prefer to form aggregates in α-Al 2 O 3 implanted to high doses while they are preferentially stabilized as Cr 3+ in MgO. The presence of Cu 2+ has been observed only in MgO and the Cu 2+ fraction decreases with higher concentration of implanted Cu atoms.