DEPENDENCE OF CURRENT-VOLTAGE CHARACTERISTICS ON AL MOLE FRACTION IN GAAS ALXGA1-XAS ASYMMETRIC DOUBLE-BARRIER STRUCTURES/

The effect of barrier Al mole fraction, 0.2 less than or equal to x le ss than or equal to 0.8, on tunneling currents has been studied for a set of asymmetric GaAs/AlxGa1-xAs double barrier structures. The barri er widths of each sample were scaled so that barrier transmission coef ficients for different samples should be approximately equivalent at t he first resonant tunneling peak. Structures were grown by molecular b eam epitaxy; by adjusting Ga and Al cell temperatures, the full range of Al mole fractions could be achieved in AlxGa1-xAs barrier layers wh ile maintaining a nearly constant growth rate of about 1 mu m/h. Curre nt-voltage measurements are in agreement with theoretical estimates an d indicate good sample quality. (C) 1997 American Vacuum Society.