Tunneling properties of AlxGa1-xAs and AlAs barriers studied by ballistic electron luminescence spectroscopy

Tunneling through barriers of AlxGa1-xAs and AlAs was studied using ballistic electron luminescence spectroscopy. The luminescence provides information on the energy distribution of the carriers after they have exited the barrier and are injected into GaAs. For electron tunneling through AlxGa1-xAs (x less than or equal to 0.3) barriers good agreement with a simple theory is obtained. The behavior of AlAs barriers is more complicated and can be explained only by assuming incoherent tunneling of electrons when their energy is above the X-point conduction band of the AlAs barrier. Hole tunneling is also observed, and the hole tunneling current is comparable to the electron current under appropriate conditions.