High mobility field effect transistors of SnO$_{\mathrm{x}}$ on glass substrates made by reactive sputtering of Sn metal

We report on the electrical properties of SnO$_{\mathrm{x}}$ thin films and the performance of their field effect transistors on glass substrates made by reactive sputtering of a Sn metal target. We investigated the electrical properties of SnO$_{\mathrm{x}}$ films as a function of the oxygen pressure. The mobility of the SnO$_{\mathrm{x}}$ films on glass substrates after post-deposition annealing at 400 C was as high as 15.3 cm$^{2}$/Vs while its carrier density was 4.42 $\times$ 10$^{18}$ cm$^{-3}$. By x-ray diffraction, we have found that the films are mixture of SnO and SnO$_{2}$ phases, suggesting possibility of further enhancement of the electrical properties if the phase can be controlled. Nevertheless, we will report on the performance of thin film transistors using polycrystalline SnO$_{\mathrm{x}}$ as the channel layer and the atomic-layer-deposited AlO$_{\mathrm{x}}$ and HfO$_{\mathrm{x}}$ as the gate oxide.