OBSERVATION OF X-BAND ELECTRON QUANTUM INTERFERENCE AND TRANSPORT THROUGH VIRTUAL STATES IN ALXGA1-XAS ALAS HETEROSTRUCTURES/

The X-band conduction electron quantum interference and its transport through GAMMA virtual state were observed in the AlxGa1-xAs/AlAs/AlxGa 1-xAs/AlAs/AlxGa1-xAs heterostructures with x=0.42, 0.45, and 0.5. Due to the existence of the deep donors, the carriers in AlxGa1-xAs elect rodes were frozen out at low temperature, and the current-voltage (I-V ) characteristics could only be measured under illumination. For x=0.4 5 and 0.5, the interference patterns were clearly observed in the diff erential conductance (dI/dV) versus voltage plot at 8.2 K and they dis appear at about 15 K for x=0.45 and 25 K for x=0.5. For x=0.42, howeve r, the interference pattern is seen only in the d2I/dV2 vs V character istics under low carrier concentration. The observation of this quantu m interference effect leads to the conclusions that the scattering rat e for X-band electrons in AlxGa1-xAs was 1.13X10(12) s-1 at 25 K for x =0.5 and 8.75X10(11) 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 an d X-GAMMA intervalley scattering.