MEASUREMENT OF HETEROJUNCTION BAND OFFSETS USING BALLISTIC-ELECTRON-EMISSION MICROSCOPY

Ballistic electron emission microscopy (BEEM) has been used to study e lectron transport across single barrier AlxGa1-xAs/GaAs heterostructur es. The structures, grown by molecular beam epitaxy, utilized a p-type delta-doped sheet to cancel the band bending near the Schottky interf ace, enabling a direct measurement of the conduction band offset at ro om temperature. The band offset at room temperature for x=0.21 is 0.19 eV and for x=0.42 is 0.33 eV. Measurements at 77 K gave values of 0.2 0 eV for x=0.21 and 0.35 eV for x=0.42. These results demonstrate that BEEM can be used to probe the transport properties of semiconductor h eterostructures which are spatially beneath the Schottky barrier.