Shallow-level muonium centre in CdS

• Author(s): Gil, J. M. ; Alberto, H. V. ; Vilão, R. C. ; Duarte, J. Piroto ; Mendes, P. J. ; Campos, N. Ayres de ; Weidinger, A. ; Krauser, J. ; Niedermayer, Ch. ; Cox, S. F. J.
• Date: 2000
• Persistent ID: http://hdl.handle.net/10316/4528
• Origin: Estudo Geral - Universidade de Coimbra
• Subject(s): II-VI semiconductors; Hydrogen-like defects; Muonium states
• Document Type: Article
• Language: English

Description

A new type of muonium defect centre has been observed in undoped CdS at low temperatures (T<20 K). The hyperfine parameters are A[short parallel]=335 (7) kHz and A[perpendicular]=199 (6) kHz (approximately 10-4 of the vacuum value) with the symmetry axis along the Cd-S bond direction. The disappearance of the centre at around 20 K is in agreement with the binding energy of a shallow centre. The extremely weak hyperfine interaction implies that the electron is only weakly bound to the muon and is distributed over a large complex of atoms in the neighborhood of the muon resembling the dilated hydrogen-like wave functions of shallow centres in a dielectric medium. Comparing the hyperfine interaction with that of free muonium, a Bohr radius of ad=26a0=1.4 nm is calculated for this defect, with a0 being the Bohr radius for the free muonium. http://www.sciencedirect.com/science/article/B6TVH-40D617P-4N/1/48a023a1c850941da0da3447d76f6f4c