Thermionic Current in Direct-Indirect Energy-Gap GaAs/AlxGa1-xAs Interfaces
Experimental and theoretical studies, on the decrease of the Richardson constant for the thermionic emission in Al-rich (z > 0.45) heterojunctions by more than 3 orders of magnitude reveal that transport in the (100) crystallographic direction, across these interfaces is still an open research field. We present a phenomenological model based on envelope wavefunctions which involves two important transport mechanisms: zero-phonon transitions due to Г - X mixing and phonon-assisted transitions. The model makes use of tunneling calculations and transmission coefficients, evaluated for the above two mechanisms. These coefficients are different from the step function used in the classical theory.
KeywordsTransmission Coefficient Thermionic Emission Thermionic Current Richardson Constant Current Expression
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