Indications of strong neutral impurity scattering in Ba(Sn,Sb)O₃ single crystals

It was recently discovered that a transparent n-type (Ba,La)SnO₃ system has electrical mobility as high as 320 cm2 V^-1 s^-1 at room temperature and superior thermal stability up to ∼500 C. To understand comparatively the carrier-scattering mechanism in the doped BaSnO₃, we investigate the physical properties of the single crystals of BaSn_1-xSb_xO₃ (x = 0.03, 0.05, and 0.10), which also show the n-type characters via the Sn site doping by Sb. Transmittance of the grown single crystals in the visible spectral region turn out to be similar to that of the (Ba,La)SnO₃ system, maintaining optical transparency. Temperature-dependent Hall effect measurements reveal that the electrical mobility at room temperature reaches as high as 79.4 cm2 V ^-1 s^-1 at a carrier density of 1.02×1020 cm ^-3, and upon increasing carrier density further, it systematically decreases nearly proportional to the inverse of the carrier density. The overall reduced mobility of the Ba(Sn,Sb)O₃ system as compared to the (Ba,La)SnO₃ system is attributed to the enhanced scattering caused by the Sb ions located in the direct conduction path. Based on the inverse proportionality between the carrier density and the electrical mobility, we suggest that the neutral impurity scattering becomes particularly strong in the Ba(Sn,Sb)O₃.