Nanostructures have been extensively studied on their electronic and photo-electronic properties for the device applications.[1-4] Among the nanostructures,the double-barrier resonant tunneling diode (RTD) nanodevices have been extensively studied for several decades due to their unique physical properties and potential device applications.Since Goldman et al.[5]reported the current bistability observed in the negative differential resistance (NDR) region of RTD devices,there has appeared a long history in debating the underlying physical mechanisms.Goldman et al.interpreted it as an intrinsic feature arising from the buildup of negative space charge in the quantum well between the two barriers.This was immediately questioned by Sollner[6] and Foster et al.[7] Later Jensen et al.[8] used time-dependent simulation and found that intrinsic high-frequency current oscillations play an important role in the bistability region.Further work also attributed the bistability to the exteal series resistance[9,10] or to the RC oscillation of the circuits.[11] All these mechanisms,however,are often correlated in realistic devices,particularly for the intrinsic ones (i.e.,charge accumulation in QWs and current oscillation).[12] As a consequence,identification of individual mechanisms still remains challenging and few experiments have been reported that study how individual mechanisms influence the transport behavior in a bistable region.In this work,by introducing charge-storing quantum dots (QDs) near the RTD quantum well,we demonstrate explicitly how the charge accumulation mechanism affects the bistable behavior of the RTD devices.