Energy levels of ytterbium in indium phosphide
C.A.J. Ammerlaan, Ingrid de Maat-Gersdorf
In its regular charge state Yb 3+ , the ytterbium impurity in indium-phosphide has the electronic configuration 4f 13 , orbital momentum L = 3 and spin S = 1/2. Ground and excited states with the total spins J = 7/2 and J = 5/2, respectively, are formed by spin-orbit interaction. The EPR spectrum of the centre provides by resolved hyperfine interactions with the isotopes 171 Yb (nuclear spin I = 1/2, natural abundance α = 14%) and 173 Yb (I = 5/2, a = 16%) direct evidence for a one-ytterbium centre in a high-symmetry environment The optical transition between the excited and ground states with an energy around wavenumber σ = 9985 cm -1 (wavelength λ = 1.0015 μm) is easily observed in photoluminescence. A cubic crystal field lifts the eight-fold degeneracy of the ground state 2 F 7/2 into a Γ 6 doublet, a F, doublet and a Γ 8 quartet, whereas the excited state 2 F 5/2 is split into a Γ 7 doublet and a Γ 8 quartet. The ordering of the crystal-field levels is still a matter of discussion, both for the ground and excited spin-orbit multiplets. Several experiments providing information on the ordering will be briefly discussed. These include the luminescence intensity, temperature, hydrostatic stress and magnetic field effects on the optical spectrum, magnetic resonance, together with a crystal-field analysis. A conclusion towards a Γ 7 - Γ 6 - Γ 8 ordering for the ground state multiplet and Γ 7 - Γ 8 for the excited state multiplet, known as the Masterov model, will be drawn.
•Jan 1, 1999•0 citations