Excitons of the Structure in Zinc-Blende In x Ga 1-x N and their Properties
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Excitons of the Structure in Zinc-Blende InxGa1-xN and their Properties Dimiter Alexandrov Department of Electrical Engineering, Lakehead University 955 Oliver Road, Thunder Bay, Ontario P7B 5E1, Canada ABSTRACT The existence of excitons of the structure in zinc-blende InxGa1-xN is reported in this paper. The LCAO electron band structure of zinc-blende InxGa1-xN is calculated as function of both the electron wave vector and the electron radius-vector. The observed optical absorption edge in Inrich regions in InxGa1-xN is explained on the basis of this electron band structure. The excitons of the structure are found on the basis of the electron band structure of zinc-blende InxGa1-xN. The binding energy and the hydrogen like energy levels of these excitons are determined. It is found that these excitons are localized. The observed photoluminescence spectrum in In-rich regions of InxGa1-xN is explained by the excitons of the structure. It is found that destroying of these excitons occurs in their interactions with hetero-junction and that the electrons and the holes of exciton origin penetrate in the semiconductor of wider energy band gap. This phenomenon is used for explanation of the observed spectral blue shift of the electroluminescence in the quantum well structures on InxGa1-xN. INTRODUCTION The quantum well structures on the basis of InxGa1-xN show interesting optical characteristics. The results obtained by Y. Narukawa et al.[1] are connected with photoluminescence spectra of quantum well structures on InxGa1-xN, and the authors explain the spectra by excitons localized in deep traps. S. Chichibu et al. [2] and P. Eliseev et al.[3] have observed blue shift of the electroluminescence in quantum well structures on InxGa1-xN. Davydov et. al. [4] have observed interesting optical absorption and photoluminescence spectrum in In-rich regions of InxGa1-xN. Existence of excitons of the structure in zinc-blende InxGa1-xN is reported in this paper. The LCAO (Linear Combination of Atomic Orbitals) electron band structure of zinc-blende InxGa1xN is calculated as function of both the electron wave-vector and the radius-vector of the quasielementary cell where the electron is localized. The energy band intervals corresponding to the different energy sub-bands are determined. The observed optical absorption edge [4] is explained on the basis of these energy intervals. Existence of excitons of the structure in zinc-blende InxGa1-xN is found. Part of the properties of these excitons is determined. The observed blue shift in [2] and [3] is explained on the basis of these excitons. Also the observed photoluminescence spectrum [4] is explained on the same basis as well. ELECTRON BAND STRUCTURE OF ZINC-BLENDE INxGA1-xN The electron band structure of zinc-blende InxGa1-xN is calculated by the method developed in [5]. The multinary crystal of zinc-blende InxGa1-xN is considered to be periodical crystal having large primitive super-cell, containing finite number of elementary cells. By definition elementary cell of the prim
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