The authors have been investigated structural, magnetic and electrical transport properties for CFAS/n-GaAs junctions. From cross sectional TEM image, RHEED and XRD patternz of thin CFAS films, CFAS films found to be grown epitaxially on GaAs, and shown L21-ordered structure for the films with substrate temperature (TCFAS) of 300°C and 400°C. It is hard to find some additional phase around the interface between CFAS and GaAs. Magnetic moment (and magnetic anisotropy energy) of CFAS increased (and decreased) with increasing TCFAS up to 300°C and decreased (and increased) at TCFAS of 400°C, respectively. The asymmetry of current(J)-voltage(V) curve for the junction with TCFAS =300°C was found to be larger than those for other junctions. It was found there is the relation between TCFAS dependence of spin signal obtained by three terminal Hanle or four terminal non-local measurement and that of magnetic moment, magnetic anisotropy field or asymmetry of J-V curve.