Abstract
The transport of X band electrons through AlAs/GaAs/AlAs/GaAs/AlAs structure with various GaAs well thickness is investigated. The resonant tunneling of X band electrons through X band double barrier is only observed when the GaAs well thickness becomes smaller than 3 nm. For thicker GaAs, the single tunneling peak is due to X band electrons tunneling through the Γ band confined states in the GaAs well. Its longitudinal optical phonon replica is also observed at temperature below 80 K, but disappears at higher temperature. This replica is due to the scattering of electrons from X band of AlAs electrode to the Γ band of GaAs in order to satisfy the momentum conservation.