Abstract:Ion bombardment provides an opportunity to study basic properties of intrinsic defects in materials since the radiation-induced disorder accumulation depends on the balance between defect generation and migration rates. In particular, variation of such parameters as irradiation temperature and ion flux, known in the literature as dose-rate effect, interconnects the macroscopically measured lattice disorder with the migration barrier of the dominating defects. In this work, we measured the dose-rate effect in m… Show more
“…VGa for the present case. Neglecting the binding energy and accounting for the recently reported VGa migration energy of ~0.8 eV [23], from the data in Fig. 3(c) the upper limit of the VGa formation energy can be estimated as ~2.4 or ~4.6…”
Section: Please Cite This Article As Doi: 101063/50070045mentioning
Silicon (Si) is an efficient n-type dopant in gallium oxide (Ga2O3) -an ultra-wide bandgap semiconductor promising in a number of applications. However, in spite of the technological importance for the device fabrication, the activation energy for Si diffusion in Ga2O3 is missing in literature. In the present work, we do such measurement in ion implanted monoclinic -Ga2O3 samples employing anneals in air ambient, also admitting the influence of the potential ion beam induced phase modifications on diffusion. Importantly, we show that Si diffusion in -Ga2O3 fits with the concentration dependent diffusion model, involving neutral and single negatively charged point defects to mediate the process; so that we assumed gallium vacancies in the corresponding charge states to assist Si diffusion in -Ga2O3 with the activation energies of 3.20.3 eV and 5.40.4 eV, respectively. Moreover, we also found that a pre-existing phase modified surface layer efficiently suppressed Si diffusion in -Ga2O3 for temperatures up to 1000 C.
“…VGa for the present case. Neglecting the binding energy and accounting for the recently reported VGa migration energy of ~0.8 eV [23], from the data in Fig. 3(c) the upper limit of the VGa formation energy can be estimated as ~2.4 or ~4.6…”
Section: Please Cite This Article As Doi: 101063/50070045mentioning
Silicon (Si) is an efficient n-type dopant in gallium oxide (Ga2O3) -an ultra-wide bandgap semiconductor promising in a number of applications. However, in spite of the technological importance for the device fabrication, the activation energy for Si diffusion in Ga2O3 is missing in literature. In the present work, we do such measurement in ion implanted monoclinic -Ga2O3 samples employing anneals in air ambient, also admitting the influence of the potential ion beam induced phase modifications on diffusion. Importantly, we show that Si diffusion in -Ga2O3 fits with the concentration dependent diffusion model, involving neutral and single negatively charged point defects to mediate the process; so that we assumed gallium vacancies in the corresponding charge states to assist Si diffusion in -Ga2O3 with the activation energies of 3.20.3 eV and 5.40.4 eV, respectively. Moreover, we also found that a pre-existing phase modified surface layer efficiently suppressed Si diffusion in -Ga2O3 for temperatures up to 1000 C.
“…For example, Ander et al have detected κ phase in the β-Ga 2 O 3 matrix upon heavy ion implants [7], even though the evolution of this process as a function of the implantation parameters has not been explored. More recently, interesting strain accumulation was observed in ion implanted α-Ga 2 O 3 [8] and β-Ga 2 O 3 [9]. However, the systematic understanding of the disorder-induced ordering in Ga 2 O 3 polymorphs was missing in literature.…”
Polymorphs are common in nature and can be stabilized by applying external pressure in materials. The pressure and strain can also be induced by the gradually accumulated radiation disorder. However, in semiconductors, the radiation disorder accumulation typically results in the amorphization instead of engaging polymorphism. By studying these phenomena in gallium oxide we found that the amorphization may be prominently suppressed by the monoclinic to orthorhombic phase transition. Utilizing this discovery, a highly oriented single-phase orthorhombic film on the top of the monoclinic gallium oxide substrate was fabricated. Exploring this system, a novel mode of the lateral polymorphic regrowth, not previously observed in solids, was detected. In combination, these data envisage a new direction of research on polymorphs in Ga 2 O 3 and, potentially, for similar polymorphic families in other materials.
“…Previously, it was demonstrated that surface amorphization in ion implanted GaN exhibits threshold-like behavior that was explained in the framework of the energy spike models 20 . However, in contrast to GaN, no amorphization was observed in ion implanted β-Ga 2 O 3 5 , 7 and the disorder enhancement in β-Ga 2 O 3 for cluster ions can be attributed to a nonlinear defect interaction as supported by a strong dose-rate effect in this material 13 . Figure 3 Amplitudes of the surface disorder peak in the ion implanted β-Ga 2 O 3 (deduced from the spectra shown in Fig.…”
Section: Resultsmentioning
confidence: 74%
“…In context of the literature interpretations of the XRD data in irradiated materials, such shoulders/peaks may be attributed to the accumulation of compressive strain 21 . Previously, we demonstrated that this strain accumulation is scaling with the disorder level in the bulk damage peak 13 . However, surprisingly enough, the strain value does not scale up with the enhanced disorder in samples implanted with the cluster ions.…”
Section: Resultsmentioning
confidence: 79%
“…To the best of our knowledge, Ga 2 O 3 is the only material where the irradiation induced polymorph transitions were demonstrated in a tractable way 5 , in contrast to the observations in other materials demonstrating much less controllable polymorphism 11 , 12 . So far, the phenomenon in Ga 2 O 3 has been studied as a function of the ion mass, dose, dose rate, and temperature 5 , 13 , 14 ; altogether demonstrating a consistent trend for the strain accumulation induced by radiation defects.…”
Ion irradiation is a powerful tool to tune properties of semiconductors and, in particular, of gallium oxide (Ga2O3) which is a promising ultra-wide bandgap semiconductor exhibiting phase instability for high enough strain/disorder levels. In the present paper we observed an interesting interplay between the disorder and strain in monoclinic β-Ga2O3 single crystals by comparing atomic and cluster ion irradiations as well as atomic ions co-implants. The results obtained by a combination of the channeling technique, X-ray diffraction and theoretical calculations show that the disorder accumulation in β-Ga2O3 exhibits superlinear behavior as a function of the collision cascade density. Moreover, the level of strain in the implanted region can be engineered by changing the disorder conditions in the near surface layer. The results can be used for better understanding of the radiation effects in β-Ga2O3 and imply that disorder/strain interplay provides an additional degree of freedom to maintain desirable strain in Ga2O3, potentially applicable to modify the rate of the polymorphic transitions in this material.
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