Rare earth substitutional impurities in germanium: A hybrid density functional theory study

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS

卷:409

Article; Proceedings Paper

Igumbor, E.^1,2  Omotoso, E.¹  Tunhuma, S. M.¹  Danga, H. T.¹  Meyer, W. E.¹ 

[1] Univ Pretoria, Dept Phys, ZA-0002 Pretoria, South Africa

[2] Samuel Adegboyega Univ, Dept Math & Phys Sci, Km 1 Ogwa Ehor Rd, Ogwa, Edo State, Nigeria

关键词: Defects;    Formation energy;    Charge state;    Rare earth;   

DOI  :  10.1016/j.nimb.2017.05.045

来源: Elsevier

【 摘 要 】

The Heyd, Scuseria, and Ernzerhof (HSE06) hybrid functional by means of density functional theory has been used to model the electronic and structural properties of rare earth (RE) substitutional impurities in germanium (REGe). The formation and charge state transition energies for the REGe (RE = Ce, Pr, Er and Eu) were calculated. The energy of formation for the neutral charge state of the REGe lies between -0.14 and 3.13 eV. The formation energy result shows that the Pr dopant in Ge (Pr-Ge) has the lowest formation energy of -0.14 eV, and is most energetically favourable under equilibrium conditions. The REGe induced charge state transition levels within the band gap of Ge. Shallow acceptor levels were induced by both the Eu (Eu-Ge) and Pr (Pr-Ge) dopants in Ge. The Ce-Ge and Er-Ge exhibited properties of negative-U ordering with effective-U values of -0.85 and -1.07 eV, respectively. (C) 2017 Elsevier B.V. All rights reserved.

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