Heterogeneous Integration of Atomically-Thin Indium Tungsten Oxide Transistors for Low-Power 3D Monolithic Complementary Inverter

In this work, the authors demonstrate a novel vertically-stacked thin film transistor (TFT) architecture for heterogeneously complementary inverter applications, composed of p-channel polycrystalline silicon (poly-Si) and n-channel amorphous indium tungsten oxide (a-IWO), with a low footprint than planar structure. The a-IWO TFT with channel thickness of approximately 3-4 atomic layers exhibits high mobility of 24 cm² V⁻¹ s⁻¹, near ideally subthreshold swing of 63 mV dec⁻¹, low leakage current below 10⁻¹³ A, high on/off current ratio of larger than 10⁹, extremely small hysteresis of 0 mV, low contact resistance of 0.44 kΩ-µm, and high stability after encapsulating a passivation layer. The electrical characteristics of n-channel a-IWO TFT are well-matched with p-channel poly-Si TFT for superior complementary metal–oxide-semiconductor technology applications. The inverter can exhibit a high voltage gain of 152 V V⁻¹ at low supply voltage of 1.5 V. The noise margin can be up to 80% of supply voltage and perform the symmetrical window. The pico-watt static power consumption inverter is achieved by the wide energy bandgap of a-IWO channel and atomically-thin channel. The vertically-stacked complementary field-effect transistors (CFET) with high energy-efficiency can increase the circuit density in a chip to conform the development of next-generation semiconductor technology.