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 (both n- and p-type) transport should be observable, however, only p-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 (∼ 80 nm), maximum currents, I , up to 60 μA μm and 90 μA μmare achieved for hole and electron conduction, respectively. Room-temperature hole (electron) mobilities up to 150 cm V s (175 cm V s) 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 for both n- and p-type conductivity was found to decrease with reduced thickness, while the ratio of I to the minimum current, I , increased. In the thinnest flakes (∼ 1.5 nm), only p-type conductivity was observed with the lowest value of I = 400 fA μm. I /I ratios as high as 5 × 10 (5 × 10) were obtained, for p- (n-channel) devices. Finally, the ambipolarity was used to demonstrate a complementary logic inverter and a frequency doubling circuit.