Broadband InxGa1-xAs quantum dot-in-a-well (DWell) solar cells are grown by stacking layers of composition-tailored InxGa1-xAs (x=1, 0.75, and 0.65) quantum dots on p-type In0.1Ga0.9As quantum wells (QWs). Doping concentration and growth temperature for the Be-doped quantum wells are optimized to enhance the conversion efficiency (eta). The broadband DWell solar cell of Be: 2 x 10(17) cm(-3) QWs grown at 570 degrees C shows the best photovoltaic characteristics of eta = 10.86%, which is 3% higher than that of the GaAs baseline solar cell. (c) 2013 Elsevier B.V. All rights reserved.