CuCl, muonium

The section on silicon is followed by a relatively brief discussion of muonium in other semiconductors. The /xLCR study of Mu in GaAs is noteworthy because again it permits a detailed model to be inferred. The important observation of the Mu— Mu transition in diamond and the unusual metastable centers in CuCl and CuBr also will be discussed. The main emphasis of this chapter will be on developments in the field since the extensive review by Patterson (1988), which covered the field up to December 1986. Other reviews on muonium in semicondutors that may be of... 

To put this in better perspective, although it is true that the hyperfine values for Mu in GaAs and GaP are closer than for any other pair of similar crystals (they differ by 30 MHz or 1.0% see Table II), there are several other cases in which A values are close but just not that close. For example, Table II shows that the hyperfine parameters for ZnS and ZnSe differ by 91 MHz or 2.6% and those for Mu" in CuCl and CuBr differ by 39 MHz or 3.1%. All of these could be explained if they corresponded to muonium in a tetrahedral interstitial surrounded by four cations to which they more strongly bond than to the anions, a suggestion similar to that of Souiri et al. (1987) and Cox (1987). Whether this could also be consistent with the closeness of the A values for Mu1 and Mu11 in CuCl and in CuBr, with the pLCR observation of appreciable anion bonding for Mu" in CuCl (see Section IV.4) and with the cluster of hyperfine parameters in SiC near the average of the diamond and silicon values (see Section IV.5), will probably require further experimentation and especially theoretical study to determine. 

Fig. 13. The temperature dependence of the precessional amplitudes (left) and relaxation rates (right) of the muonium centers observed in the copper halides. The open and filled triangles or squares are for Mu7 and Mu77 respectively. Note the similarity of the Cul data to that for Mu7 in CuCl and CuBr, suggesting that a transition to another center occurs in Cul but that the product has not been observed. From Kiefl et al. (1986b).

---