High performance of eco-friendly magnesium system thermoelectric material by the controlled defect and composition.

在Mg_2SiSn系热电半导体中引入肖特基缺陷或Fraenkel缺陷，这些缺陷改变了半导体的导电类型。这是由于Mg原子的Fraenkel缺陷产生电子作为施主，间隙Mg原子的Schoenkel缺陷产生空穴作为受主，晶界缺陷使Mg_2SiSn的电子浓度显著降低，即晶界缺陷形成了电子陷阱能级。通过这些缺陷控制载流子浓度是可能的，通过控制缺陷和成分，p型Mg2SiSn的性能提高了约3倍。

Mg_2SiSn system thermoelectric semiconductor, which introduced the schottky defect or the Fraenkel defect, changed the conduction type by those defects. Those causes were 1) an electron as a donor was produced by the Fraenkel defect of Mg atom, 2) a hole as an acceptor was produced by the schottky defect of the interstitial Mg atom.The electron concentration of Mg2SiSn with the grain boundary defect was decreased remarkably, this is, the electronic trap-level was formed by the grain boundary defect. Therefore, a hole became dominant and p-type conduction was shown.The controlling of carrier concentration by these defects was possible.The performance of p-type Mg2SiSn by the controlling of defect and composition was improved about 3 times.