Crystalline Silicon Solar Cells With Coannealed Electron- and Hole-Selective SiCx Passivating Contacts

We present electron- and hole-selective passivating contacts based on wet-chemically grown interfacial SiOx and overlying in-situ doped silicon carbide (SiCx) deposited by plasma-enhanced chemical vapor deposition. After annealing at 850 degrees C, excellent surface passivation on the p-type planar crystalline silicon wafer is obtained for both electron- and hole-selective contacts. Their potential is demonstrated at the device level by employing a simple process flow, in which the junction formation of the two polarities is achieved with a single coannealing step. Both-side-contacted patterning-free planar p-type cells with an area of 4 cm(2) and screen-printed metallization reach a fill factor of 83.4% and a open-circuit voltage of 726 mV. Zirconium-doped indium oxide with excellent optoelectrical properties is used as a front electrode. The decrease in the parasitic absorption in the front electrode results in higher photogenerated current. By realizing front-side-textured and rear-side-planar p-type cells, an efficiency of up to 22.6% is achieved.