Ballistic elecron emission microscopy of InAsGa1 − xAlxAs relaxed heterostructure interfaces

The barrier height of Au/InAs/AlGaAs as a function of AlAs content (x = 0–1.0) was measured using ballistic electron emission microscopy (BEEM). The InAs interlayer was introduced here to change the contact behaviour between Au and AlGaAs. The measured dependence of barrier height with Al content (x) was found to differ from that in the diret AuAlGaAs contact. Also, the variation of barrier height over space was successfully recorded, which suggests the influence of local potentials (defects) upon local barriers. The STM image of the InAs surface revealed highly relaxed surface structures, which may explain the observed inhomogeneity of the InAsAlGaAs interface.