TUNNELING THROUGH ALXGA1-XAS SINGLE BARRIERS UNDER HYDROSTATIC-PRESSURE

Transport properties of AlxGa1-xAs single barrier tunneling diodes wit h barrier compositions ranging from x=0.38 to x=1.00 are investigated. The pressure dependence of the tunneling current is used to monitor t wo distinct transport channels in these devices. The first channel is governed by the conduction-band offset between GAMMA-like states in th e GaAs contacts and the AlxGa1-xAs barrier, which is independent of pr essure. The barrier height for the second channel is determined by the X minima and not by the GAMMA minimum in the AlxGa1-xAs layer. Only t his second conduction-band profile is pressure dependent. The crossove r from the first to the second transport regime is observed directly i n the sample with x=0.50.