Zeeman spectroscopy of the internal transition 4T1 to 6A1 of Fe3+ ions in ZnO

Abstract

In this work, internal [Formula: see text]T[Formula: see text]A[Formula: see text] transitions within the half-filled 3d shell of Fe[Formula: see text] in extremely pure chemical vapor deposition (CVD)-grown ZnO layers were investigated by means of high-resolution, low-temperature continuous wave (cw) photoluminescence (PL), time-resolved PL, photoluminescence excitation (PLE) spectroscopy, Zeeman spectroscopy, and deep level transient spectroscopy (DLTS). For comparison, Zeeman spectroscopy measurements were also performed on commercially available, hydrothermally grown ZnO bulk crystals. Magnetic fields up to [Formula: see text] were applied parallel and perpendicular to the c-axis of the ZnO crystals in order to investigate the fine structure of included states. The splitting pattern of emission lines related to [Formula: see text]T[Formula: see text] [Formula: see text] [Formula: see text]A[Formula: see text] Fe[Formula: see text] transitions was theoretically modeled by a Hamiltonian matrix including the crystal field in cubic and trigonal symmetries and spin–orbit interaction for the complete excited [Formula: see text]T[Formula: see text] state. The extremely pure ZnO used in this study, in direct comparison to hydrothermally grown ZnO, allows the identification, investigation, and description of single isolated Fe[Formula: see text] defects in ZnO for the first time—different from literature reports hitherto, which seemingly were recording data on Fe–Li complexes. The resulting exact energy-level scheme in combination with the experimental data leads to a re-evaluation of [Formula: see text]T[Formula: see text] [Formula: see text] [Formula: see text]A[Formula: see text] Fe[Formula: see text] transitions in ZnO.