Carrier control of p and n in type-I crystal clathrates Ba 8Ga16 Ge30's (BGG's) is studied for their single crystals. The polycrystalline precursors with regulated various stoichiometric compositions are employed for single crystal growth under excess amount Ga as a flux. Hall coefficient measurements prove that both p and n type BGG single crystals are produced by modifying the relative ratios between the endohedral alkaline-earth atoms and the Ga atoms residing in the framework. ICP analyses together with Rietveld refinement based on the high resolution synchrotron X-ray diffraction suggests that the occupancy of Ba is less than one, and this explains the reason why p type can be possible in BGGs in contrast to the fact only n type is obtained in Sr8Ga16Ge 30's. Superconductivity is not observed when the high doping levels are searched.
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