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

Abstract

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/cm² 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.