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

The homojunction based on Ti 3 C 2 T x MXene-doped In 2 O 3 and indium oxide as the channel layer is realized in high-performance metal oxide thin film transistors (TFTs). Doping of MXene into In 2 O 3 results in n-type semiconductor behavior, realizing tunable work function of In 2 O 3 from 5.11 to 4.79 eV as MXene content increases from 0 to 2 wt.%. MXene-doped In 2 O 3 -based homojunction TFT presents optimal performance with electron mobilities of greater than 27.10 cm 2 /(V s) at 240 °C, far exceeding the maximum mobility of 3.91 cm 2 /(V s) for single-layer In 2 O 3 TFTs. The improved performance originates from boosting of a two-dimensional electron gas (2DEG) formed at carefully engineered In 2 O 3 /MXene-doped In 2 O 3 oxide homojunction interface. Besides, the transformation in conduction mechanism leads to better stability of MXene-doped In 2 O 3 homojunction devices compared to undoped bilayer In 2 O 3 . Low-frequency noise further illustrates that doping MXene into In 2 O 3 helps to reduce the device trap density, demonstrating excellent electrical performance. A resistor-loaded unipolar inverter based on In 2 O 3 /0.5% MXene-In 2 O 3 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.