p- and n-Type Ba8Ga16Ge30 studied by X-ray photoelectron spectroscopy

The first band for n-type BGG is sensitive to temperature, while the second band is sensitive for p-type BGG. The change of Ba/Ga ratio, from which the carrier type is controlled in this system, modifies the positions of Ga residing at the larger (Ga-Ge)24 outer cage. This modification in the surrounding framework is responsible for the large differences observed in electronic properties of p- and n-BGGs in this clathrate family.