We discovered that La-doped BaSnO3 with the perovskite structure has an unprecedentedly high mobility at room temperature while retaining its optical transparency. In single crystals, the mobility reached 320 cm^2(Vs)^-1 at a doping level of 8x10^19 cm^-3, constituting the highest value among wide-band-gap semiconductors. In epitaxial films, the maximum mobility was 70 cm^2(Vs)^-1 at a doping level of 4.4x10^20 cm^-3. We also show that resistance of (Ba,La)SnO3 changes little even after a thermal cycle to 530 Deg. C in air, pointing to an unusual stability of oxygen atoms and great potential for realizing transparent high-frequency, high-power functional devices.Comment: 15 pages, 3 figure

Transparent electronic materials are increasingly in demand for a variety of optoelectronic applications, ranging from passive transparent conductive windows to active thin film transistors. suggest that the doped BaSnO 3 system holds great potential for realizing all perovskite-based, transparent high-temperature high-power functional devices as well as highly mobile two-dimensional electron gas via interface control of heterostructured films.

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We studied the conduction mechanism in Sb-doped BaSnO3 epitaxial films, and compared its behavior with that of the mechanism of its counterpart, La-doped BaSnO3. We found that the electron mobility in BaSnO3 films was reduced by almost 7 times when the dopant was changed from La to Sb, despite little change in the effective mass of the carriers. This indicates that the scattering rate of conduction electrons in the BaSnO3 system is strongly affected by the site at which the dopants are located. More importantly, we found that electron scattering by threading dislocations also depends critically on the dopant site. We propose that the large enhancement of scattering by the threading dislocations in Sb-doped BaSnO3 films is caused by the combination effect of the change in the distribution of Sb impurities in the films, the formation of the Sb impurity clusters near the threading dislocations, and the conduction electron clustering near the Sb impurities.

We report p-doping of the BaSnO3 (BSO) by replacing Ba with K. The activation energy of K-dopants is estimated to be about 0.5 eV. We have fabricated pn junctions by using K-doped BSO as a p-type and La-doped BSO as an n-type semiconductor. I-V characteristics of these devices exhibit an ideal rectifying behavior of pn junctions with the ideality factor between 1 and 2, implying high integrity of the BSO materials. Moreover, the junction properties are found to be very stable after repeated high-bias and high-temperature thermal cycling, demonstrating a large potential for optoelectronic functions.