Back contacted a-Si:H/c-Si heterostructure solar cells

This paper shows how the amorphous/crystalline silicon technology can be implemented in the interdigitated back contact solar cell design. We have fabricated rear junction, backside contact cells in which both the emitter and the back contact are formed by amorphous/crystalline silicon heterostructure, and the grid-less textured front surface is passivated by a double layer of amorphous silicon and silicon nitride, which also provides an anti-reflection coating. The entire self-aligned mask and photolithography-free process is performed at temperature below 300 degrees C with the aid of one metallic mask to create the interdigitated pattern. An open circuit voltage of 687 mV has been measured on a 0.5 Omega cm p-type monocrystalline silicon wafer. On the other hand, several technological aspects that limit the fill factor (50%) and the short circuit current density (32 mA/cm(2)) still need improvement. We show that the uniformity of the deposited amorphous silicon layers is not influenced by the mask-assisted deposition process and that the alignment is feasible. Moreover, this paper investigates the photocurrent limiting factors by one-dimensional modeling and quantum efficiency measurements. (c) 2008 Elsevier B.V. All rights reserved.