Potential distribution and capacitance of abrupt heterojunctions

The transition region analysis of an abrupt heterojunction is extended to include the effects of mobile carriers' charge in the space charge regions. Deviations from the depletion model are obtained when the wide band-gap semiconductor is heavier-doped-This is due to a non-negligible potential drop across the narrow band-gap semiconductor at an isotype (i.e. n-n or p-p) heterojunction, and to an inversion layer at the interface in the same semiconductor at an anisotype (i.e. p-n or n-p) heterojunction. The C −2 versus V plots are acceptable, straight lines having slopes in agreement with the depletion model predictions, but the intercept voltages differ. A constant electric dipole at the interface causes a similar effect.