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RE-doped β-Ga2O3 seems attractive for future high-power LEDs operating in high irradiation environments. In this work, we pay special attention to the issue of radiation-induced defect anisotropy in β-Ga2O3, which is crucial for device manufacturing. Using the RBS/c technique, we have carefully studied the structural changes caused by implantation and post-implantation annealing in two of the most commonly used crystallographic orientations of β-Ga2O3, namely the (-201) and (010). The analysis was supported by advanced computer simulations using the McChasy code. Our studies reveal a strong dependence of the structural damage induced by Yb-ion implantation on the crystal orientation, with a significantly higher level of extended defects observed in the (-201) direction than for the (010). In contrast, the concentration and behavior of simple defects seem similar for both oriented crystals, although their evolution suggests the co-existence of two different types of defects in the implanted zone with their different sensitivity to both, radiation and annealing. It has also been found that Yb ions mostly occupy the interstitial positions in β-Ga2O3 crystals that remain unchanged after annealing. The location is independent of the crystal orientations. We believe that these studies noticeably extend the knowledge of the radiation-induced defect structure, because they dispel doubts about the differences in the damage level depending on crystal orientation, and are important for further practical applications. [ABSTRACT FROM AUTHOR]

Monte Carlo (MC) simulations are a powerful tool for the analysis of ion-solid interactions. The MC code McChasy (Monte Carlo CHAnneling SYmulation) allows the evaluation of Rutherford Backscattering Spectrometry spectra in the Channeling mode to quantify implantation damage. The code works on common personal computers and takes into account randomly displaced atoms as well as certain types of extended defects. In this paper, we report recent improvements of the McChasy code, including a unique approach to the calculation of impact parameters between ions and target atoms in three dimensions (along with computing thermal vibrations also in three dimensions). Furthermore, the use of a rotation matrix to provide different orientations of dislocation lines and an updated model of edge dislocations were also implemented in the code. Dislocation parameters are obtained directly from high-resolution Transmission Electron Microscopy micrographs. Two case studies are presented to highlight the importance of these improvements: Ni-implanted Al was analyzed as an example of a crystal mainly containing dislocations; Er-implanted ZnO was studied, revealing the strength of MC analysis for materials containing a mixture of different defect types, namely, randomly displaced atoms and dislocations. [ABSTRACT FROM AUTHOR]

Rare earth-doped zinc oxide (ZnO:RE) systems are attractive for future optoelectronic devices such as phosphors, displays, and LEDs with emission in the visible spectral range, working even in a radiation-intense environment. The technology of these systems is currently under development, opening up new fields of application due to the low-cost production. Ion implantation is a very promising technique to incorporate rare-earth dopants into ZnO. However, the ballistic nature of this process makes the use of annealing essential. The selection of implantation parameters, as well as post-implantation annealing, turns out to be non-trivial because they determine the luminous efficiency of the ZnO:RE system. This paper presents a comprehensive study of the optimal implantation and annealing conditions, ensuring the most efficient luminescence of RE3+ ions in the ZnO matrix. Deep and shallow implantations, implantations performed at high and room temperature with various fluencies, as well as a range of post-RT implantation annealing processes are tested: rapid thermal annealing (minute duration) under different temperatures, times, and atmospheres (O2, N2, and Ar), flash lamp annealing (millisecond duration) and pulse plasma annealing (microsecond duration). It is shown that the highest luminescence efficiency of RE3+ is obtained for the shallow implantation at RT with the optimal fluence of 1.0 × 1015 RE ions/cm2 followed by a 10 min annealing in oxygen at 800 °C, and the light emission from such a ZnO:RE system is so bright that can be observed with the naked eye. [ABSTRACT FROM AUTHOR]

RE-doped β-Ga2O3 seems attractive for future high-power LEDs operating in high irradiation environments. In this work, we pay special attention to the issue of radiation-induced defect anisotropy in β-Ga2O3, which is crucial for device manufacturing. Using the RBS/c technique, we have carefully studied the structural changes caused by implantation and post-implantation annealing in two of the most commonly used crystallographic orientations of β-Ga2O3, namely the (-201) and (010). The analysis was supported by advanced computer simulations using the McChasy code. Our studies reveal a strong dependence of the structural damage induced by Yb-ion implantation on the crystal orientation, with a significantly higher level of extended defects observed in the (-201) direction than for the (010). In contrast, the concentration and behavior of simple defects seem similar for both oriented crystals, although their evolution suggests the co-existence of two different types of defects in the implanted zone with their different sensitivity to both, radiation and annealing. It has also been found that Yb ions mostly occupy the interstitial positions in β-Ga2O3 crystals that remain unchanged after annealing. The location is independent of the crystal orientations. We believe that these studies noticeably extend the knowledge of the radiation-induced defect structure, because they dispel doubts about the differences in the damage level depending on crystal orientation, and are important for further practical applications. [ABSTRACT FROM AUTHOR]

Accumulation and transformation of defects formed in bulk ZnO crystals at room temperature upon 300 keV Er ions bombardment have been thoroughly examined using complementary techniques: Rutherford Backscattering Spectrometry in ion Channeling mode (RBS/C), X‐Ray Reflectivity (XRR), and X‐Ray Diffraction (XRD). Evaluation of RBS/C spectra has been performed using Monte Carlo (MC) simulations (McChasy software). Two defect types have been indicated: point defects (randomly displaced atoms, RDA) and extended ones (edge dislocations, DIS). Depth‐distributions of RDA and DIS turned out to be shifted toward deeper regions of ZnO crystals (relative to Er‐ions range) while DIS are localized even deeper than RDA. The MC simulations reveal three regions of defects accumulation separated by two regions of rapid defects transformation occurring at a certain critical Er fluence. Strain, suggested to be a driving force of defect transformation, has been determined using simulations of the XRD profiles based on the dynamical theory of X‐ray diffraction (MROX software). The presented research can help to better understand the interaction between impurity Er ions and ZnO target atoms during the implantation process. Hence, implantation conditions, for example, for luminescence purpose may now be more efficiently chosen based on the results discussed. [ABSTRACT FROM AUTHOR]