Manipulation of electron transport in graphene by nanopatterned electrostatic potential on an electret

Abstract

The electron transport characteristics of graphene can be finely tuned using local electrostatic fields. Here, we use a scanning probe technique to construct a statically charged electret gate that enables in-situ fabrication of graphene devices with precisely designed potential landscapes, including p-type and n-type unipolar graphene transistors and p-n junctions. Electron dynamic simulation suggests that electron beam collimation and focusing in graphene can be achieved via periodic charge lines and concentric charge circles. This approach to spatially manipulating carrier density distribution may offer an efficient way to investigate the novel electronic properties of graphene and other low-dimensional materials.

Reconfigurable Multifunctional Ambipolar Polymer‐Blend Transistors with Improved Switching‐Off Capability

“…The charge trapping and de‐trapping in the insulator‐matrix is switchable and reversible, which enables to erase the previous state and reprogram the device for another state. [ 39 ] Moreover, as there are traps for both holes and electrons leading to the threshold voltages for the accumulation of mobile charges, the actual pinch‐off region of the ambipolar transistor is wider than that shown in Figure 1c and smaller compensation potentials could effectively lower the off‐state current.…”

“…[ 40 ] Reading the post‐synaptic current at drain and applying the spike pulse at gate electrode are implemented simultaneously, which enables to concurrently perform the signal transmission and self‐learning processes. [ 7,9,39 ] As the drain voltage and gate voltage are applied simultaneously during the pulse, the charges are non‐uniformly injected and trapped in the insulator‐matrix. The drain current is sensitive to the non‐uniformly trapped charges at V G = 0 V, which could effectively tune the off‐state current as demonstrated in Figures 3,4, even if the number of injected charges at room temperature is relatively small.…”

“…Actually, besides additional electrodes, any methods (e.g., polarized ferroelectrics and charged electrets) which can provide gradually varied compensation potential would eliminate the asymmetric potential along the channel under certain gate and drain voltages. [37][38][39] Therefore, in principle an appropriate gate voltage in combination with an extra compensation potential can be designed to prevent the injection and accumulation of both holes and electrons to obtain an off-state with low current (Figure 1b). As gate voltage scans, holes or electrons could be synchronically and symmetrically accumulated along the channel to quickly achieve a high on-current (Figure 1b).…”

Reconfigurable Multifunctional Ambipolar Polymer Transistors with Improved Switching-off Capability Upon Non-Uniformly Distributed Compensation Potential

“…The charges are pre-injected into the insulator-matrix by gate-stress, and through adjusting the gate and drain voltages, the distribution of the injected charges could be modulated to generate different compensation potential profiles along the channel to realize different final device performance. The charge trapping and de-trapping in the insulator-matrix is switchable and reversible, which enables to erase the previous state and reprogram the device for another state 39 . Moreover, as there are traps for both holes and electrons leading to threshold voltages for the accumulation of mobile charges, the actual pinch-off region of the ambipolar transistor is wider than that shown in Fig.…”

“…Actually, besides additional electrodes, any methods (e.g. polarized ferroelectrics and charged electrets) which can provide gradually varied compensation potential to the channel can eliminate the asymmetric potential along the channel under certain gate and drain voltages [36][37][38][39] . Therefore, appropriate gate voltage and external compensation potential can be designed to prevent the injection and accumulation of neither holes nor electrons to obtain an off-state with low current (Fig.…”