ABSTRACT
The structure and the arrangement of layers of different bandgap materials in the resonant tunneling diode (RTD) are described. Its basic operation is explained. The operation is easily understood in comparison to the Fabry-Perot interferometer in optics. Two types of tunneling mechanisms, viz. coherent and incoherent tunneling, are distinguished with reference to relative magnitudes of scattering time and lifetime of metastable states in the quantum well. The Tsu-Esaki formula for current density of the RTD is derived assuming coherent tunneling. Its disagreement with experiments is interpreted to be arising from non-inclusion of incoherent scattering. Using a modified transmission coefficient by taking into account inelastic scattering, as suggested by Stoney and Lee, an agreement between theory and experiment is much closer.
