Photo-, cathodo-, and electroluminescence from erbium and oxygen co-implanted GaN

Abstract

Efficient Er-related photo-, cathodo-, and electroluminescence at 1539 nm was detected from Er and O co-implanted n-type GaN on sapphire substrates. Several combinations of Er and O implants and postimplant annealing conditions were studied. The Er doses were in the range (0.01-5)ϫ10 15 ions/cm 2 and O doses (0.1-1)ϫ10 16 ions/cm 2 . GaN films implanted with 2ϫ10 15 Er 2ϩ /cm 2 at 350 keV and co-implanted with 10 16 O ϩ /cm 2 at 80 keV yielded the strongest photoluminescence intensity at 1539 nm. The annealing condition yielding the strongest Er-related photoluminescence intensity was a single anneal at 800°C ͑45 min͒ or at 900°C ͑30 min͒ in flowing NH 3 . The optimum O:Er ratio was found to be between 5:1 and 10:1. Co-implanting the GaN:Er films with F was also found to optically activate the Er, with slightly ͑20%͒ less photoluminescence intensity at 1539 nm compared to equivalent GaN:Er,O films. The Er-related luminescence lifetime at 1539 nm was found to depend on the excitation mechanism. Luminescence lifetimes as long as 2.95Ϯ0.15 ms were measured at 77 K under direct excitation with an InGaAs laser diode at 983 nm. At room temperature the luminescence lifetimes were 2.35Ϯ0.12, 2.15Ϯ0.11, and 1.74Ϯ0.08 ms using below-band-gap excitation, above-band-gap excitation, and impact excitation ͑reverse biased light emitting diode͒, respectively. The cross sections for Er in GaN were estimated to be 4.8ϫ10 Ϫ21 cm 2 for direct optical excitation at 983 nm and 4.8ϫ10 Ϫ16 cm 2 for impact excitation. The cross-section values are believed to be within a factor of 2-4.

Green, red and infrared Er-related emission in implanted GaN:Er and GaN:Er,O samples

“…We observed an enhancement of PL intensity for samples without oxygen coimplantation, in contrast with previous ones. 1 The quenching of PL emission can be related with the presence of oxygen related complexes. Residual defects are evident on the RBS aligned spectrum of Fig.…”

“…1 The presence of oxygen promotes an enhancement of the PL intensity 1,8 as well as a reduction of the Er 3ϩ PL quenching under below band gap excitation. 8 From PL and photoluminescence excitation different set of PL lines have been assigned to different Er site locations and/or Er-O ͑or other defects and impurities͒ related complexes.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] These are due to the intraionic transition of the Er 3ϩ between the two lowest spin-orbit levels 4 I 13/2 → 4 I 15/2 . Besides the well known infrared emission, visible luminescence from higher excited levels was also observed in molecular beam epitaxy ͑MBE͒ [8][9][10] and reactive sputtering 11 grown samples.…”

Visible and Infrared Rare-Earth Activated Electroluminescence From Erbium Doped GaN

“…III-V semiconductors doped with rare-earth elements have also been used 10,11,12,13,14,15,16,17,18 and have advantages compared to narrow bandgap materials 19 . The advantage of Nakamura's devices is their extremely high quantum efficiency 1 (~5%), whereas RE doped devices offer multiple color emission, wavelength-limited only by the RE element(s) chosen and not by the band gap energy of the semiconductor.…”

Visible and Infrared Rare-Earth Activated Electroluminescence from Erbium Doped GaN

“…III-V semiconductors doped with rare-earth elements have also been used 10,11,12,13,14,15,16,17,18 and have advantages compared to narrow bandgap materials 19 . The advantage of Nakamura's devices is their extremely high quantum efficiency 1 (~5%), whereas RE doped devices offer multiple color emission, wavelength-limited only by the RE element(s) chosen and not by the band gap energy of the semiconductor.…”