| The addition of multiquantum well structures was found to increase the efficiency of InP based solar cells as the absorption region of the cell extends into the infrared region of the spectral response of the multiquantum structure. The efficiency of the solar cells that are under investigation was not up to the expected levels. In order to understand the reason behind this decreased efficiency, an investigation of electron/hole emission from chemical beam epitaxy grown InAsxP1-x/InP multiquantum solar cell structures has been carried out using deep level transient spectroscopy.; The two types of solar cell structures under investigation showed six electron traps. Detailed depth profile analysis showed that the electron traps are extended over the whole multiquantum region, including interfaces.; The electron trap E3 in the sample with higher arsenic composition was found to exhibit strong electric field dependence. The mid-gap electron trap E3, with its higher capture cross-section acts as a strong recombination center. To the best of our knowledge this is a new finding presented here for the first time, which can play an important role in improving the efficiency of InP-based multiquantum well solar cells. |
