Electron Band Structure of MnGaN

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1040-Q05-02

Electron Band Structure of MnGaN Dimiter Alexandrov1, Nikolaus Dietz2, Ian Ferguson3, and Hang Yu1 1 Department of Electrical Engineering, Lakehead University, 955 Oliver Road, Thunder Bay, P7B5E1, Canada 2 Department of Physics and Astronomy, Georgia State University, Atlanta, GA, 30302-3965 3 School of Elect. & Comp. Engineering, Georgia Institute of Technology, Atlanta, GA, 303320250 ABSTRACT Properties of MnxGa1-xN semiconductor alloy are investigated on the basis of LCAO electron band structure of this semiconductor. The authors model this alloy on the basis of Mn substitutions on Ga sites and it is identified that the ternary semiconductor MnxGa1-xN has two tetrahedral binary constituents – GaN and MnN. It is found that the sp3 hybrid orbital of the N atom attracts an electron from the 3d orbital of the Mn atom and thus the Mn-N bonding becomes of sp3 type. In this way the total electron spin of the 3d orbital of the Mn atom becomes 3/2, which determines that the energy levels 4F, 4D, 4P and 4G belonging to this orbital to be occupied. LCAO electron band structure of wurtzite MnxGa1-xN for points Γυc1 and Γυv15 (υ = 1, 2, 3, 4, 5) is calculated by previously developed method and the positions of the levels 4F, 4D, 4P and 4G in this structure are determined. It is found dependence of the total electron spin of the Mn atom on the position of the Fermi level in the electron band diagram of MnxGa1-xN. Also it is found that the total spin depends on electron inter-band transitions as well. The optical properties of the wurtzite MnxGa1-xN are determined as well. INTRODUCTION MnxGa1-xN semiconductor alloy is important for investigation due to expectations of unique properties. The alloys related to GaN show interesting optical properties such as both optical absorption and photo-luminescence spectra [1 – 6]. Especially it is valid for the semiconductor InxGa1-xN that shows wide variation of the optical absorption edge due to existence of tunnel optical absorption and variation of the maximum of the PL spectrum due to excitons of the structure [7 – 9]. From other side the spin of the electrons belonging to 3d orbital of the Mn atom can be considered to be a precondition for magnetic properties of MnxGa1-xN with a possible application in the spintronics. It determines the scientific efforts for investigation of the impact of Mn atom, which substitutes on Ga site in the structure of MnxGa1-xN [10 – 14]. In this paper the authors present results of theoretical study of the properties of MnxGa1-xN based on its Linear Combination of Atomic Orbitals (LCAO) electron band structure. Investigation of the behavior of the 3d and 4s valence electrons of Mn atom substituting on Ga site in the structure of GaN crystal lattice is presented in terms of both creation of ion-covalent bonds and electron spin. Calculation of LCAO electron band structure of MnxGa1-xN is performed and the positions of the 3d electron levels of Mn atom are presented. Both the optical absorption edge and the maximum of the PL spectrum of MnxGa1-