Ambipolar transport in van der Waals black arsenic field effect transistors

Black arsenic (BAs) is an elemental van der Waals semiconductor that is promising for a wide range of electronic and photonic applications. The narrow bandgap and symmetric band structure suggest that ambipolar (bothn- andp-type) transport should be observable, however, onlyp-type transport has been experimentally studied to date. Here, we demonstrate and characterize ambipolar transport in exfoliated BAs field effect transistors. In the thickest flakes (similar to 80 nm), maximum currents,I-max, up to 60 mu A mu m(-1)and 90 mu A mu m(-1)are achieved for hole and electron conduction, respectively. Room-temperature hole (electron) mobilities up to 150 cm(2)V(-1)s(-1)(175 cm(2)V(-1)s(-1)) were obtained, with temperature-dependence consistent with a phonon-scattering mechanism. The Schottky barrier height for Ni contacts to BAs was also extracted from the temperature-dependent measurements.I(max)for bothn- andp-type conductivity was found to decrease with reduced thickness, while the ratio ofI(max)to the minimum current,I-min, increased. In the thinnest flakes (similar to 1.5 nm), onlyp-type conductivity was observed with the lowest value ofI(min)= 400 fA mu m(-1).I-max/I(min)ratios as high as 5 x 10(5)(5 x 10(2)) were obtained, forp- (n-channel) devices. Finally, the ambipolarity was used to demonstrate a complementary logic inverter and a frequency doubling circuit.