Contribution of a single quantum dots layer in intermediate band solar cells: A capacitance analysis

- The C-V characteristics of QDs differ from that of a bulk by the appearance of a plateau.
- The plateau is due to QDs, which are full with holes.
- The charge in the QD is determined by the dot density and the position of the hole energy levels.
- The capacitance depends on the width of the depletion region.

Theoretical model and numerical analysis of charge accumulation within a single GaSb quantum dots layer embedded in GaAs-based Schottky diode is performed. We hereby give an analytical calculation of the capacitance-voltage (C-V) characteristic of GaAs-based Schottky barrier structure incorporating GaSb self-assembled quantum dots layer. The Schottky barrier is derived in different bias voltage region based on solving analytically Poisson׳s equation, including the effects of the dots size dispersion and the Fermi statistics of the holes in the quantum dots. The numerical simulation of capacitance-voltage curves exhibits a plateau that is caused by the high carrier concentration and the saturation of the quantum dots levels upon the applied voltage. These results are in good agreement with experiments done by Hwang et al.