Finite element study of exciton energies and optical absorption in InAs/GaAs multi-quantum dots under electric fields

This study provides a theoretical analysis of exciton energies and optical absorption coefficients in InAs/GaAs multi-quantum dots (MQDs) under the influence of external electric fields and structural variations. The calculations are performed within the effective mass approximation, taking into account both electron–heavy hole and electron–light hole excitons. The results show that for narrow barrier widths, exciton energies decrease with increasing electric field, whereas for wider barriers they display a non-monotonic dependence, governed by carrier spatial separation and the resulting changes in Coulomb interaction. Structural dimensions are also found to be critical: enlarging the quantum dot width (Ldx) causes a redshift in absorption peaks due to reduced confinement, while increasing the barrier width (Lbx) leads to a blueshift as a result of weaker electron–hole overlap. Moreover, when applying an electric field with either the barrier width fixed or the dot width fixed at 0.278a_GaAs=3nm, a pronounced blueshift of absorption peaks emerges for both heavy and light holes, attributed to weakened Coulomb binding. Overall, the findings highlight that structural and electrical tuning offers an effective route to control excitonic properties, with promising implications for the development of InAs/GaAs MQD-based optoelectronic devices.