Temperature dependence photoreflectance spectroscopy of InAs/GaAs quantum dot solar cell with AlGaAs potential barrier

Quantum dot solar cells (QDSCs) were fabricated with a 2.8 nm Al 0.3 Ga 0.7 As potential barrier, and photoreflectance (PR) spectroscopy was performed to investigate the potential barrier effect in the localized electric field of QDSCs. PR spectroscopy was used to evaluate localized electric fields of QDSC with/without potential barrier through the FKO analysis. The PR spectra showed the optical transitions from QDs, wetting layer and Franz-Keldysh oscillation (FKO). When the QD embedded in Al 0.3 Ga 0.7 As potential barriers, spectral intensity of each transition was increased drastically due to the modulation efficiency increment caused by enhancement of carrier confinement between potential barrier. From the structural consideration, the electric field of 30.7 kV/cm originated from the p-i-n interface electric filed. On the other hand, the higher electric field of the 130 kV/cm originated from localized electric field from the QD region. The strength of localized electric fields of QDSC with potential barrier is smaller than those of QDSC without barrier because of the carrier confinement-induced field screening effect.