Optical and Electrical Study of Defects in GaN In Situ Doped with Eu3+ Ion Grown by OMVPE

A silicon/europium-codoped GaN epilayer (GaN:Si,Eu3+) and a control sample (GaN:Si) have been investigated using optical spectroscopy and various deep-level transient spectroscopy (DLTS) techniques. Three electron traps in GaN:Si,Eu3+, as well as one electron trap and one hole trap in GaN:Si, were observed in the temperature range from 35 K to 400 K by DLTS. High-resolution Laplace DLTS revealed multiple, closely spaced defect energy levels associated with trap B of GaN:Si,Eu3+ and trap D of GaN:Si, respectively. Minority-carrier transient spectroscopy (MCTS) measurements revealed a shallow hole trap in GaN:Si,Eu3+, whose presence was validated using the rare-earth-structured isovalent (RESI) hole trap model. The identified DLTS energy traps were compared with other energy traps reported in literature. Also, the energy transfer mechanism between the GaN host and Eu3+ ion was considered and discussed using the combination of electrical and optical studies reported here and in literature.