Materials, Vol. 15, Pages 187: Nondegenerate Polycrystalline Hydrogen-Doped Indium Oxide (InOx:H) Thin Films Formed by Low-Temperature Solid-Phase Crystallization for Thin Film Transistors
Materials doi: 10.3390/ma15010187
We successfully demonstrated a transition from a metallic InOx film into a nondegenerate semiconductor InOx:H film. A hydrogen-doped amorphous InOx:H (a-InOx:H) film, which was deposited by sputtering in Ar, O2, and H2 gases, could be converted into a polycrystalline InOx:H (poly-InOx:H) film by low-temperature (250 &deg;C) solid-phase crystallization (SPC). Hall mobility increased from 49.9 cm2V&minus;1s&minus;1 for an a-InOx:H film to 77.2 cm2V&minus;1s&minus;1 for a poly-InOx:H film. Furthermore, the carrier density of a poly-InOx:H film could be reduced by SPC in air to as low as 2.4 &times; 1017 cm&minus;3, which was below the metal&ndash;insulator transition (MIT) threshold. The thin film transistor (TFT) with a metallic poly-InOx channel did not show any switching properties. In contrast, that with a 50 nm thick nondegenerate poly-InOx:H channel could be fully depleted by a gate electric field. For the InOx:H TFTs with a channel carrier density close to the MIT point, maximum and average field effect mobility (&mu;FE) values of 125.7 and 84.7 cm2V&minus;1s&minus;1 were obtained, respectively. We believe that a nondegenerate poly-InOx:H film has great potential for boosting the &mu;FE of oxide TFTs.
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