Spatial distribution of deep level traps in GaNAs crystals

GaNAs crystals grown by the metalorganic vapor-phase epitaxy (MOVPE) method are characterized by plane-view electron beam induced current (EBIC) and d eep-level transient spectroscopy (DLTS). Localized deep-level traps with a diameter of 3-5 mum are clearly observed from EBIC analysis. The DLTS analy sis shows that the dominant deep-level traps have energy levels of E-v + 0. 58 eV and E-c - 0.72 eV. Such deep level traps are eliminated by annealing at 700 degreesC. From our analysis, the change in the spatial distribution of deep-level traps due to annealing correlates strongly with the change in the FL intensity, indicating that observed deep-level traps are one of the major factors which degrade the optical properties of the GaNAs crystals. In addition to these localized traps, the inhomogeneity of minority diffusi on length is also detected by EBIC. (C) 2000 Elsevier Science B.V. All righ ts reserved.