New spectroscopic data of erbium ions in GaN thin films

Abstract

Optical properties of erbium ions in MBE-grown GaN-thin films are reported. Three types of sites were identified using site selective laser excitation. The main center is ascribed to the Er 3+ ions substituted in the Ga sub-lattice while the two other centers are assigned to Er-related defects. The lifetimes of the 4 S 3/2 and 4 I 13/2 multiplets of the main center are strongly quenched with increasing Er concentration. The complex decay profile of the visible fluorescence and its concentration dependence were modeled and interpreted using the diffusion-limited model.The dynamics of the infrared emission at 1.54 m from the 4 I 13/2 multiplet after excitation in the visible range is discussed. The crystal field strength of Er 3+ in GaN was deduced from the overall crystal field splitting of the ground multiplet. Comparison of the results with those obtained in inorganic materials indicates that the rare earth is well embedded in the semiconductor host and not in a impurity oxide phase.

Site Multiplicity of Rare Earth Ions in Iii-Nitrides

“…Different sites are resolved by the coincidence of excitation and emission lines in particular groupings. Dierolf et al find two 'majority' and up to four 'minority' groupings in CEES spectra of GaN:Er, in broad agreement with previous results [16,17].…”

Rare earth doped III-nitrides for optoelectronics

“…Dierolf et al [45] have provided a very clear recent example of site-selective spectroscopy of MBE-doped GaN:Er; wavelength-stepped laser excitation and recording of luminescence spectra by a CCD-spectrograph, produces Combined ExcitationEmission Spectra (CEES). Different luminescent sites may be readily identified in these spectra by the coincidence of excitation and emission lines in particular groupings; Dierolf et al find two 'majority' and up to four 'minority' groupings in CEES spectra of GaN:Er, in broad agreement with previous results [46,47]. These observations mainly concern internal transitions of the RE ions, below the host band-gap in terms of photon energy, with some sites appearing to require 'feeding' by others (intersite energy transfer).…”

Carrier lifetime in erbium-doped GaN waveguide emitting in 1540 nm wavelength

“…Although EDFA in fiber-optic systems uses 980 or 1480 nm optical pumping, 1 investigations in Er-doped GaN so far were limited by using either green pump in 530 nm wavelength window 12,13 or UV pumping at 350 nm. 10,11 In fact, pumping at near infrared wavelengths to populate carriers in 4 I 13/2 energy band has an advantage of providing higher photon conversion efficiency than using higher energy photons such as in UV and green wavelengths, which avoided transitions through intermediate energy levels and the associated energy loss during these transitions.…”