Electron multiplication in AlxGa1−xAs/GaAs heterostructures

We have measured the electron multiplication characteristics of thin (∼0.1 μm) AlxGa1−xAs(500 Å)/GaAs(500 Å) single heterostructures with 0.3⩽x⩽0.6, grown in a p-i-n configuration. In these devices, at low electric fields, the electron multiplication occurs mainly in the latter half of the i region because of dead space effects. As the electric field increases the multiplication behavior converges to that of the equivalent alloy. Our measurements show that the electron multiplication in these structures never exceeds that of GaAs. A simple Monte Carlo simulation suggests that the advantage obtained from the conduction band edge step down from AlxGa1−xAs to GaAs is offset by the energy loss via higher phonon emission in the AlxGa1−xAs layer.