On the spectral response of interdiffused quantum dot ensembles embedded in the intrinsic region of InGaAs/GaAs quantum dot solar cells

Abstract Semiconductor nanostructures , such as, quantum dots (QDs), embedded in the absorber layer of solar cells (SCs) are high priority research topics in the field of QDSCs. The dot size distribution is one of the critical factors governing the spectral response (SR) of these embedded nanostructures. The dot aspect ratio (AR) may serve as a useful and accurate parameter for analyzing such size distribution, as it helps in addressing the cumulative variation of dot size in the lateral, as well as growth direction. Furthermore, due to interdiffusion, the sharp heterointerface between the dot material and surrounding matrix is likely to get diluted. The incorporation of such a phenomenon in the theoretical model of QDSC seems to be demanding for accurately evaluating the performance of fabricated cells. Based on the above, this work is an effort to propose a unified analytical model for the SR of QD ensembles embedded in the intrinsic region of InGaAs/GaAs p- i -n QDSCs, taking into account the variation of dot AR and changes in the potential profile due to interdiffusion, which, for the first time, being analyzed in a common platform. Through our proposed model, we have also investigated the effects of dot AR, size deviation and extent of interdiffusion on the SR and photocurrent density of the cell structure under consideration. At each stage of our computation, we have compared the performance of interdiffused dots with the conventional modeling approach representing as-grown structures, to uncover suitable explanations justifying the degraded performance of fabricated QDSCs as compared to their other competitors.