Optical bandgap and stress variations induced by the formation of latent tracks in GaN under swift heavy ion irradiation

Exploring swift-heavy ion irradiation of InGaN/GaN multiple quantum wells for green-emitters: the use of Raman and photoluminescence to assess the irradiation effects on the optical and structural properties

“…According to the references, these S e values are above and below the track formation threshold in GaN. 18,19 Table 1 summarizes the irradiation conditions (energy as well as electronic and nuclear losses) and the samples' labels.…”

“…17,18 To induce the creation of ion tracks and intermixing at interfaces, the electronic energy loss should be higher than a specific threshold (S e th ) that depends on the material properties (e.g., density and specific heat capacity). For GaN, the track formation threshold value is still under debate, with some contradictory values reported: (i) B15 keV nm À1 , 18 (ii) B17 keV nm À1 , 19 and (iii) higher than 22.8 keV nm À1 . 20 In addition to the possibility of QWI with an expected low density of point defects, the higher penetration depth of SHIs allows their implantation in the substrate instead of in the active region.…”

Fullerene irradiation leading to track formation enclosing nitrogen bubbles in GaN material

“…Undeniably, studies performed on this material have demonstrated that ion irradiation, at normal incidence with a high velocity, leads to discontinuous track formation [23]. In addition, an increase of the electronic stopping power induces latent tracks displaying more continuous morphology/shape [22]. Others studies found that swift heavy ion irradiation on GaN produces disordered tracks and generates lattice stress [24,25].…”

“…Ion track formation is governed by the electronic energy loss process according to various phenomenological models: Coulomb explosion, lattice relaxation and thermal spike [17][18][19][20][21]. High energetic ions, with Se above 17 keV/nm, usually produce tracks along the ion path in gallium nitride [22]. Undeniably, studies performed on this material have demonstrated that ion irradiation, at normal incidence with a high velocity, leads to discontinuous track formation [23].…”

“…The impact produced by the projectile exhibits a circular area i.e. a track containing extended defects such as dislocations [22,26]. In the surface region, other defects, such as nanoholes, were identified in the case of irradiation at grazing incidence [27].…”