Possible donor and acceptor energies for Mu in ZnSe

Multiple charge-state transitions are observed for muonium in heavily compensated ZnSe. A paramagnetic resonance signal for the state known as MuIIMuII is present to ∼350K, but has decreased amplitude between 30 and ∼200K, disappearing completely in one sample. Satellite lines in the MuIIMuII spectrum identify it as Mu0Mu0 at the T-site with Se neighbours. We obtain an ionization energy of ∼0.4eV for this Mu donor location. Loss of MuIIMuII and growth of a diamagnetic signal near 25 K had been assigned to electron capture by Mu0Mu0, and its loss near 80 K to e-e- emission from Mu-Mu- to the conduction band. We offer an alternative explanation for the loss of Mu-Mu- amplitude, and suggest that high-temperature growth of diamagnetic amplitude be associated with Mu acceptor ionization. This alternative model gives thermodynamic levels for Mu in ZnSe that fit well into the overall picture of H in semiconductors.