Optimisation of the physical properties of InAs/InGaAs/GaAs QDs heterostructures embedded p-i-n GaAs solar cell

摘要

In order to enhance absorption at infrared range for GaAs-based solar cell, we have grown multi-stacked InAs/InGaAs/GaAs quantum dots (QDs) heterostructure in the active region by Solid-Source Molecular Beam Epitaxy (SS-MBE). Two different families of dots were observed in the photoluminescence (PL) spectra. Temperature-dependent study was carried out at 10-240 K temperature range. Distinctive, asymmetric shape located in the high energy for the PL spectra of the QD solar cell sample can be deconvoluted in two sub-bands. From the temperature-dependent PL measurement, the two sub-bands are associated with the ground-state emission from the two families of InAs dots with different size. Besides, the spectral response of multi-stacked InAs/InGaAs QD solar cells extends the photo-absorption spectra towards a wavelength longer than the GaAs bandgap of 1280 nm. However, the QDs solar cell shows an enhanced short-circuits current density of 7.8 mA/cm~2 compared to the GaAs reference cell. The performance of the QD solar cells indicates that the InAs/InGaAs/GaAs QD heterostructures facilitate the fabrication of highly stacked QD layers that are suitable for solar cells devices requiring thick QD layers for sufficient light absorption.