Inductively coupled plasma deposited amorphous silicon alloys using industrial equipment for heterojunction silicon solar cells

One of the most promising advanced solar cell designs for <; 100 μm thin silicon wafers is the heteroj unction silicon wafer solar cell (HET), with a very high efficiency potential with cost-effective low-temperature processing. In collaboration with German company Singulus Technologies and other industrial collaborators, SERIS is developing a pilot line suitable for mass production of HET cells. Initial experiments on the inductively coupled plasma deposition of a-Si:H(i) and compositionally similar alloy films such as a-SiO_x:H(i) have yielded very good results compatible with high-voltage HET solar cells, with the passivation quality of a-SiO_x:H(i) being consistently higher, and far less sensitive to the deposition temperature compared to a-Si:H(i). In fact, a-SiO_x:H(i) has a stable process window of more than 200°C that is suitable for the production environment. The wider process window can be attributed to suppressed epitaxial growth and incubation layer thickness in the a-SiO_x:H(i) layer at high deposition temperatures.