Co-diffusion thin layer of phosphorus and boron for preparation of silicon BSF solar cell

Co-diffusion processing is emerging as a promising simplified process for manufacture of terrestrial back surface field (BSF) solar cells. In this work, we present results about co-diffusion of two dopant elements (phosphorus and boron) in a single thermal cycle in order to form emitter and BSF thin layer simultaneously. According to the measured sheet resistance, it was found that uniform, stable and controllable diffusion layers on front and back surface of silicon wafer can be obtained with co-diffusion method. Using the co-diffusion method, some silicon back surface field (BSF) solar cells with an efficiency of more than 12% (at AMI) were prepared. The measurement results of minority carrier lifetime show that boron diffusion in back side of silicon wafer has a gettering effect on the p-n junction area and can improve the characteristics of solar cells.