Energy-band engineering by 2D MXene doping for high-performance homojunction transistors and logic circuits

Abstract

The homojunction based on Ti3C2Tx MXene-doped In2O3 and indium oxide as the channel layer is realized in high-performance metal oxide thin film transistors (TFTs). Doping of MXene into In2O3 results in n-type semiconductor behavior, realizing tunable work function of In2O3 from 5.11 to 4.79 eV as MXene content increases from 0 to 2 wt.%. MXene-doped In2O3-based homojunction TFT presents optimal performance with electron mobilities of greater than 27.10 cm2/(V s) at 240 °C, far exceeding the maximum mobility of 3.91 cm2/(V s) for single-layer In2O3 TFTs. The improved performance originates from boosting of a two-dimensional electron gas (2DEG) formed at carefully engineered In2O3/MXene-doped In2O3 oxide homojunction interface. Besides, the transformation in conduction mechanism leads to better stability of MXene-doped In2O3 homojunction devices compared to undoped bilayer In2O3. Low-frequency noise further illustrates that doping MXene into In2O3 helps to reduce the device trap density, demonstrating excellent electrical performance. A resistor-loaded unipolar inverter based on In2O3/0.5% MXene-In2O3 TFT has demonstrated full swing characteristics and a high gain of 13. The effective doping of MXene into constructed homojunction TFTs not only contributes to improved stability, but also provides an effective strategy for designing novel homojunction TFTs for low-cost oxide-based electronics.