Abstract: A metamorphic multijunction solar cell having a growth semiconductor substrate with a top surface having a doping in the range of 1x1018 to 1x1020 charge carriers/cm3; a window layer for a top (light facing) subcell formed directly on the top surface of the growth substrate; a sequence of layers of semiconductor material forming a solar cell directly on the window layer; a surrogate substrate on the top surface of the sequence of layers of semiconductor material, wherein a portion of the semiconductor substrate is removed so that only the high doped surface portion of the substrate, having a thickness in the range of 0.5 ?m to 10 ?m, remains.