Defect and crystal structure variation in Tl-doped TlGaTe2 semiconductor alloys: An experimental and theoretical study
JOURNAL OF ALLOYS AND COMPOUNDS, vol.1038, 2025 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 1038
- Publication Date: 2025
- Doi Number: 10.1016/j.jallcom.2025.182773
- Journal Name: JOURNAL OF ALLOYS AND COMPOUNDS
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Chimica, Compendex, INSPEC, Public Affairs Index
- Azerbaijan State University of Economics (UNEC) Affiliated: No
Abstract
In this work, the structural and defect characteristics of TlGaTe2 semiconductors doped with 5 % and 9 % thallium (Tl) were investigated using X-ray diffraction (XRD), positron annihilation lifetime spectroscopy (PALS), Doppler broadening spectroscopy (DBS), and first-principles calculations. XRD analysis confirmed the preservation of the tetragonal I4/mcm symmetry across all compositions, with increasing Tl content inducing local microstrain without long-range structural transitions. PALS revealed a dual defect evolution mechanism: sequential filling of micropores by Tl atoms alongside the creation of monovacancies (primarily monoGa). This was supported by the non-monotonic behavior of positron lifetime components and the ortho-positronium annihilation ratio. Electron Momentum Distribution (EMD) analysis further corroborated this, indicating Tl substitution for Ga and a modified bonding environment due to Tl occupying micropores. DBS showed a transition to a more homogeneous defect distribution with increased Tl concentration. These findings provide a detailed understanding of the complex defect dynamics induced by Tl doping in TlGaTe2, offering potential for defect engineering to tailor its properties for advanced technological applications.