This book summarizes author's work of process development and device characterization on traditional front junction silicon heterojunction solar cells and all back contact IBC silicon heterojunction solar cell at Univeristy of Delaware from summer of 2006 to the end of 2008.The work demonstrates a high Voc close to 700mV in surface textured front junction silicon heterojunction solar cells and high efficiency all back contact solar cells by the support of U.S. Department of Energy.