High Mobility in a Stable Transparent Perovskite Oxide
We discovered that La-doped BaSnO 3 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 V -1 s -1 at a doping level of $8\times 10^{19}$ cm -3 , constituting the highest val...
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| Published in | Applied physics express Vol. 5; no. 6; pp. 061102 - 061102-3 |
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| Main Authors | , , , , , , , , , , |
| Format | Journal Article |
| Language | English |
| Published |
The Japan Society of Applied Physics
01.06.2012
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| Online Access | Get full text |
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| Summary: | We discovered that La-doped BaSnO 3 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 V -1 s -1 at a doping level of $8\times 10^{19}$ cm -3 , constituting the highest value among wide-band-gap semiconductors. In epitaxial films, the maximum mobility was 70 cm 2 V -1 s -1 at a doping level of $4.4\times 10^{20}$ cm -3 . We also show that resistance of (Ba,La)SnO 3 changes little even after a thermal cycle to 530 °C in air, pointing to an unusual stability of oxygen atoms and great potential for realizing transparent high-frequency, high-power functional devices. |
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| Bibliography: | (a) BaSnO 3 has an almost ideal cubic perovskite with its lattice constant of 4.116 $Å$, and a SnO 6 octahedron inside the unit cell is plotted. (b) Optical microscopy images of the flux-grown BaSnO 3 (29.9 μm thick) and (Ba,La)SnO 3 (36.8 μm thick) single crystals, showing their optical transparency. (c) X-ray $\theta$--$2\theta$ scan results show the ($00l$) peaks in both single crystals and epitaxial thin films grown on SrTiO 3 (001) substrate. (d) The reciprocal space mapping of (103) peaks shows that the lattice constants are 4.127 $Å$ in the growth direction and 4.107 $Å$ on the plane, implying that there is a slight compressive strain on our 200-nm-thick film. $Q_{X}$ and $Q_{Z}$ are the in and out of plane components of a reciprocal space vector. (a) Resistivity $\rho$ and (b) mobility $\mu$ of the (Ba,La)SnO 3 thin films and single crystals are plotted as functions of carrier density $n$ at 300 K. The experimental data are shown as solid symbols while the dashed lines are guides to the eyes. The dotted lines represent $\mu\propto n^{-1}$ for the single crystal and $\mu\propto n^{1/2}$ for the thin films. Inset in (a) shows the temperature dependent resistivity of single crystal ($n = 1.62\times 10^{20}$ cm -3 ). (a) Temperatures and gas atmosphere were varied according to the profile in the upper panel and the resultant resistance variation is plotted in the lower panel. The film was 100 nm thick and the temperature was maintained at 530 °C for 5 h. (b) The corresponding resistance vs temperature is plotted. Resistance decreased (increased) by about 8% under Ar (O 2 ) atmosphere in 5 h at 530 °C while it changed by only about 1.7% in air. |
| ISSN: | 1882-0778 1882-0786 |
| DOI: | 10.1143/APEX.5.061102 |