Gigahertz Integrated Circuits Based on Complementary Black Phosphorus Transistors

Black phosphorus (BP) has attracted enormous interest for logic applications due to its unique electronic properties. However, pristine BP exhibits predominant p-type channel conductance, which limits the realization of complementary circuits unless an effective n-type doping is found. Here, a practical approach to transform the conductivity of BP from p-type to n-type via a spatially controlled aluminum (Al) doping is proposed. Symmetrical threshold voltage for the pair of p-type and n-type BP field-effect transistors can be achieved by tuning the Al doping concentration. The complementary inverter circuit shows a clear logic inversion with a high voltage gain of up to approximate to 11 at a supply voltage (V-DD) of 1.5 V. Simultaneously, a high noise margin of 0.27 x V-DD is achieved for both low (NML) and high (NMH) input voltages, indicating excellent noise immunity. Moreover, a three-stage ring oscillator with a theoretical frequency above 1.8 GHz and microwatt level power dissipation is modeled, which shows a low propagation delay per stage. This study demonstrates a practical approach to fabricate high performance complementary integrated circuits on a homogenous BP channel material, paving the way toward complex cascaded circuits and sensor interface applications.