Double-Peak N-Shaped Negative Differential Resistance in a Quantum Dot Field Effect Transistor

Double-peak N-shaped negative differential resistance (NDR) with a high peak-to-valley ratio is observed in the output characteristics of a GaAs-based modulation-doped field effect transistor with InAs quantum dots in the barrier layer (QDFET). One NDR peak with a higher source-drain voltage V_DS is explained as the real-space transfer (RST) of high-mobility electrons in the channel into the quantum dots layer, while the other with a lower V_DS is caused by the high-mobility RST electrons in the channel into the modulation-doped AlGaAs barrier layer on the other side. We depict a point how a thinner Schottky barrier layer provides a stronger potential, opening a possibility of two-directional channel electron transfer when a much higher V_G is applied. The result suggests that the QDFET can be an attractive candidate for high-speed logic application and memory devices.