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ZnO single crystals were implanted with Ar ions with an energy of 100 keV and different fluences. Ferromagnetic behaviour is observed at room temperature after implantation. This behaviour is suppressed after consecutive annealings at 400 and 500 °C. Although trace transition metal impurities have been identified in the virgin samples, it is shown that they cannot account for the observed magnetic behaviour that is assigned to the presence of implantation-induced lattice defects.

Al x Ga 1−x N alloys, covering the entire compositional range (0 ≤ x ≤ 1), were implanted at room temperature with 200 keV argon (Ar) ions to fluences ranging from 1 × 10 13 to 2 × 10 16 Ar/cm 2 . The damage formation mechanisms and radiation resistance of Al x Ga 1−x N alloys were investigated combining in situ Rutherford backscattering spectrometry/channeling (RBS/C) and ex situ X-ray diffraction (XRD) in order to assess the damage profiles and the elastic response of the material to radiation. For all compounds, damage buildup proceeds in four stages revealing a saturation of the defect level for high fluences without any sign of amorphization. Surprisingly, in this high fluence regime, RBS/C reveals higher defect levels in samples with high AlN concentrations in contrast to the common believe that AlN is more radiation resistant than GaN. A model is proposed ascribing this behavior to a lower defect recombination cross section at room temperature combined with the formation of stable extended defects. The processes are probably dependent on the collision cascade density, that is, the mass of the implanted ions. XRD shows that implantation leads to the incorporation of large lattice strain in the implanted layer which increases with increasing fluence. Above a threshold fluence, an abrupt change of the elastic properties of the crystals is observed and strain saturates in the entire implanted region. This threshold fluence is reached earlier for GaN than for Al x Ga 1−x N alloys with x > 0.

We report on the growth kinetics of semipolar ͑11− 22͒ InGaN layers by plasma-assisted molecular beam epitaxy. Similarly to ͑0001͒-oriented InGaN, optimum growth conditions for this crystallographic orientation correspond to the stabilization of two atomic layers of In on the growing InGaN surface, and the limits of this growth window in terms of substrate temperature and In flux lie at same values for both polar and semipolar material. However, in semipolar samples, the incorporation of In is inhibited, even for growth temperatures within the Ga-limited regime of polar InGaN growth.

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Self-assembled GaN quantum dots ͑QDs͒ stacked in superlattices ͑SL͒ with AlN spacer layers were implanted with Europium ions to fluences of 10 13 , 10 14 , and 10 15 cm −2 . The damage level introduced in the QDs by the implantation stays well below that of thick GaN epilayers. For the lowest fluence, the structural properties remain unchanged after implantation and annealing while for higher fluences the implantation damage causes an expansion of the SL in the ͓0001͔ direction which increases with implantation fluence and is only partly reversed after thermal annealing at 1000°C. Nevertheless, in all cases, the SL quality remains very good after implantation and annealing with Eu ions incorporated preferentially into near-substitutional cation sites. Eu 3+ optical activation is achieved after annealing in all samples. In the sample implanted with the lowest fluence, the Eu 3+ emission arises mainly from Eu incorporated inside the QDs while for the higher fluences only the emission from Eu inside the AlN-buffer, capping, and spacer layers is observed.