High temperature annealing of Er implanted GaN

Lattice location and optical activation of rare earth implanted GaN

“…Here we would also like to correct a mistake in one of our previous publications [16] [12-15, 17, 18]. While epitaxial regrowth takes place at 1000°C with a rate around 100 Å/min, only annealing at 1200°C under 1 GPa of nitrogen has so far been successful in achieving nearcomplete recovery in some cases [14], while in others the reproducibility of the high-temperature high-pressure treatment proved to be not entirely reliable. In the case of Er, the maximum substitutional fractions for these high-dose implanted samples were around 30-50% with a possible contribution of some Er displaced along the c-axis [19].…”

“…Annealing around 600°C starts the damage recovery, however, even following annealing at 1000°C for 2 min under flowing N 2 it is not complete and at best only minimum Ga RBS yields down to around 0.10 were achieved. Only annealing at 1200°C under 1 GPa of nitrogen (done at the Unipress Institute in Warsaw) occasionally resulted in samples where the RBS Ga yield was again similar to virgin samples [14]. Fig.…”

“…Measurements have been done for GaN samples implanted at energies of 150-160 keV with fluences in the range 5×10 14 [12,13]. In other terms, with respect to the c-axis, 100% of Er atoms had on average the same locations as the Ga atoms, of which around 30% were randomly distributed in the lattice.…”

Influence of O and C co-implantation on the lattice site of Er in GaN

“…3 With respect to the effect of O on Er luminescence in GaN, varying results are found in the literature. 4 While some articles [5][6][7] state a beneficial influence on the luminescence, others report no obvious benefit 8 or even a negative impact [9][10][11] on Er emission intensity. It has been pointed out 4,9 that the annealing temperature is possibly crucial, with O co-doping being beneficial only for GaN samples that are not annealed above 900°C.…”

“…12 Several publications have already addressed the lattice location of Er in GaN and GaN:O. Rutherford backscattering/channeling ͑RBS/C͒ experiments performed for higher doses (Ϸ10 15 cm Ϫ2 ) of implanted Er found 50%-70% on substitutional Ga (S Ga ) sites. 6,10 It was also concluded that the addition of oxygen stabilizes Er on Ga sites. Another RBS/C study 11 shows 32% of Er on S Ga sites while a fraction of 13% is displaced along the ͓0001͔ direction.…”