The role of defects on the efficiency of intermediate band solar cells based on III-V semiconductors

We have investigated the electrically active defects of two intermediate band solar cells of GaAs with quantum dots of InAs and GaAs spacer layers grown at 630 °C and 700 °C by deep level transient spectroscopy (DLTS) and Laplace DLTS. An increment in trap concentration is observed when using the lowest temperature to grow the spacer layers, agreeing with the reduction in conversion efficiency, short-circuit current and open-circuit voltage of the device. The introduction of a relatively high trap concentration due to the temperature cycle [490-700] °C used to grow the active region comprising the InAs quantum dot layers has also been observed, suggesting a major deterioration of the solar cells.