Symmetric complementary logic inverter using integrated black phosphorus and MoS₂ transistors

The operation of an integrated two-dimensional complementary metal¡Voxide¡Vsemiconductor inverter with well-matched input/output voltages is reported. The circuit combines a few-layer MoS₂ n-MOSFET and a black phosphorus (BP) p-MOSFET fabricated using a common local backgate electrode with thin (20 nm) HfO₂ gate dielectric. The constituent devices have linear threshold voltages of-0.8 V and +0.8 Vand produce peak transconductances of 16 μgS μgm^-1 and 41 μgS μgm^-1 for the MoS₂ n-MOSFET and BP p-MOSFET, respectively. The inverter shows a voltage gain of 3.5 at a supply voltage, V_DD ≥Q=2.5 V, and has peak switching current of 108 μgA and off-state current of 8.4 μgA (2.4 μgA) at V_IN=0 (V_IN=2.5 V). In addition, the inverter has voltage gain greater than unity for V_DD ≥ 0.5 V, has open butterfly curves for V_DD ≥ 1 V, and achieves static noise margin over 500mV at V_DD=2.5 V. The voltage gain was found to be insensitive to temperature between 270 and 340 K, and AClarge and small-signal operation was demonstrated at frequencies up to 100 kHz. The demonstration of a complementary 2D inverter which operates in a symmetric voltage window suitable for driving a subsequent logic stage is a significant step forward in developing practical applications for devices based upon 2D materials.