Observation of X‐band electron quantum interference and transport through virtual states in Al_xGa_1−xAs/AlAs heterostructures

The X‐band conduction electron quantum interference and its transport through Γ virtual state were observed in the Al_xGa_1−xAs/AlAs/Al_xGa_1−xAs/AlAs/Al_xGa_1−xAs heterostructures with x=0.42, 0.45, and 0.5. Due to the existence of the deep donors, the carriers in Al_xGa_1−xAs electrodes were frozen out at low temperature, and the current‐voltage (I‐V) characteristics could only be measured under illumination. For x=0.45 and 0.5, the interference patterns were clearly observed in the differential conductance (dI/dV) versus voltage plot at 8.2 K and they disappear at about 15 K for x=0.45 and 25 K for x=0.5. For x=0.42, however, the interference pattern is seen only in the d²I/dV² vs V characteristics under low carrier concentration. The observation of this quantum interference effect leads to the conclusions that the scattering rate for X‐band electrons in Al_xGa_1−xAs was 1.13×10¹² s⁻¹ at 25 K for x=0.5 and 8.75×10¹¹ s⁻¹ at 15 K for x=0.45, respectively. For x=0.42, the scattering events at 8.2 K were dominated by electron–electron and X–Γ intervalley scattering.