Melt growth and properties of bulk BaSnO single crystals.

We present the first-time growth of bulk BaSnO single crystals from the melt by direct solidification, their basic electrical and optical properties as well as their structural quality. Our measurement of the melting point (MP) of BaSnO amounts to 1855 °C  ±  25 K. At this temperature an intensive decomposition and non-stoichiometric evaporation takes place as the partial pressure of SnO(g) is about 90 times higher than that of BaO(g).

Observation of the triplet metastable state of shallow donor pairs in AlN crystals with a negative-U behavior: a high-frequency EPR and ENDOR Study.

Theoretical predictions about the n-type conductivity in nitride semiconductors are discussed in the light of results of a high-frequency EPR an ENDOR study. It is shown that two types of effective-mass-like, shallow donors with a delocalized wave function exist in unintentionally doped AlN. The experiments demonstrate how the transformation from a shallow donor to a deep (DX) center takes place and how the deep DX center can be reconverted into a shallow donor forming a spin triplet and singlet states.