Drain induced barrier increasing in multilayer ReS2

Abstract

The interlayer tunneling resistivity (R-int) and Thomas-Fermi charge screening effects play critical roles in the carrier transport of two-dimensional (2D) multilayer devices. For example, the vertical electric field modifies the R-int, resulting in a channel migration along the c-axis. However, because R-int varies considerably with the drain electric field in addition to the vertical field, the effective contribution of each layer to the total current varies with the drain bias (V-D). Here, we demonstrate a drain induced barrier increasing (DIBI) in 2D multilayer rhenium disulfide (ReS2) as a possible reverse short channel effect (rSCE). The reported decoupled layer interaction and much higher interlayer resistivity of ReS2 compared to other 2D materials allow us to observe the DIBI clearly. As V-D increases, the effective amplitude of R-int decreases dramatically, leading to (i) the increase of off-current, (ii) the enhancement of field-effect mobility, and (iii) the blue shift of the flat band voltage (V-FB), which is in sharp contrast to a previous report on a short-channel bulk-Si device with drain induced barrier lowering (DIBL). We attribute this difference to the weakened Fermi level (E-F) tunability when the channel migrates from the bottom to the top surface of ReS2, and to an opposite electrostatic force resulting from V-D, implying the increased importance of V-D-dependent R-int in the carrier transport mechanism of 2D multilayer systems. The V-D-dependent Coulomb scattering parameter probed via a low frequency (LF) noise analysis provides deeper insights for the channel shift. Our findings pave the way for understanding and exploiting the fundamental charge transport mechanism in 2D multilayer systems.