Ion implanted dopants in GaN and AlN: Lattice sites, annealing behavior, and defect recovery

Abstract

The recovery of structural defects in gallium nitride (GaN) and aluminum nitride (AlN) after implantation of In+111 and Sr+89 in the dose range (0.1–3) 1013 cm−2 and ion energies of 60–400 keV has been investigated as a function of annealing temperature with emission channeling (EC) and perturbed γγ angular correlation spectroscopy. The implanted In and Sr atoms occupied substitutional sites in heavily perturbed surroundings of point defects after room temperature implantation. No amorphization of the lattice structure was observed. The point defects could be partly removed after annealing to 1473 K for 10–30 min. Lattice site occupation of implanted light alkalis, Na+24 in GaN and AlN as well as Li+8 in AlN, were also determined by EC as a function of implantation and annealing temperature. These atoms occupied mainly interstitial sites at room temperature. Lithium diffusion and the occupation of substitutional sites was observed in GaN and AlN at implantation temperatures above 700 K. A lattice site change was also observed for sodium in AlN, but not in GaN after annealing to 1073 K for 10 min.

Emission channeling studies of Pr in GaN

“…On the other hand, the remaining damage in GaN is difficult to anneal. Incomplete annealing of implantation disorder and the absence of a pronounced recovery step up to 900°C has been reported previously [10,[12][13][14]23]. In accordance with this we also did not observe a major recovery step up to 900°C, although the decrease in the rms displacement of Pr indicates some local atomic rearrangement.…”

“…The main reason that the sublattice preference could not be derived from the experimental data is the fact that simulations were only available for electron channeling along the c-axis, see also Ref. [12].…”

Influence of crystal mosaicity on axial channeling effects and lattice site determination of impurities

“…18 Ronning et al 19 and Lorenz et al 20 have observed a similar decrease in substitutional fraction for this temperature range in perturbed angular correlation (PAC) experiments on In-implanted AlN, which was attributed to the oxidation of the surface layer.…”

Lattice sites of Na dopants in ZnO

“…Lattice location experiments with 24 Na have been previously performed also in hexagonal GaN and AlN [41,60], that in many aspects have quite similar properties to ZnO. It is hence not surprising that also in these two III-nitride semiconductors co-existence of 24 Na on interstitial sites near the octahedral position and on substitutional cation Ga or Al sites was found, although the maximum interstitial fractions in the RT asimplanted state were with 40-60% lower than in ZnO.…”