Self-Assembled Nanodielectrics for Solution-Processed Top-Gate Amorphous IGZO Thin-Film Transistors

Metal oxide semiconductors, such as amorphous indium gallium zinc oxide (a-IGZO), have made impressive strides as alternatives to amorphous silicon for electronics applications. However, to achieve the full potential of these semiconductors, compatible unconventional gate dielectric materials must also be developed. To this end, solution-processable self-assembled nanodielectrics (SANDs) composed of structurally well-defined and durable nanoscopic alternating organic (e.g., stilbazolium) and inorganic oxide (e.g., ZrO and HfO) layers offer impressive capacitances and low processing temperatures (T ≤ 200 °C). While SANDs have been paired with diverse semiconductors and have yielded excellent device metrics, they have never been implemented in the most technologically relevant top-gate thin-film transistor (TFT) architecture. Here, we combine solution-processed a-IGZO with solution-processed four-layer Hf-SAND to fabricate top-gate TFTs, which exhibit impressive electron mobilities (μ_SAT = 19.4 cm² V^-1 s^-1) and low threshold voltages (V_th = 0.83 V), subthreshold slopes (SS = 293 mV/dec), and gate leakage currents (10^-10 A) as well as high bias stress stability.