Occurrence of Nonlinear Electron Mobility in GaAs/InxGa1−xAs Coupled Double Quantum Well FET

The mobility, µ of electrons shows oscillating behavior in an asymmetric GaAs/InxGa1-xAs Quantum Well (QW) Field Effect Transistor (FET) structure. So as to analyze µ, we take asymmetric doping concentrations, varying Nd1 in the substrate barrier and keeping Nd2 constant in surface barrier. The well widths W1 and W2 are also asymmetrically changed such that the sum (W1 + W2) remains constant. Resonance can be achieved for the subband energy states between the two QWs for a set of W1 and W2 by varying Nd1. A considerable variation is observed in spreading of subband wave functions near resonance that affect the subband mobilities through intersubband effects, thus causing a drop in µ. We show that dip in µ enhances by decreasing the difference in W1 and W2. The results of nonlinearity in µ can help in analyzing the characteristics of the QWFET devices near resonance.