Ultrathin Crystalline Silicon Heterojunction Solar Cell Integrated on Silicon-on-Insulator Substrate

To achieve power generation on IC chips, a hydrogenated amorphous silicon (a-Si:H)/crystalline silicon (c-Si) heterojunction solar cell was designed and fabricated on silicon-on-insulator substrate, where a 9-
$\mu \text{m}$
epitaxial p-type c-Si layer served as light absorption layer and the buried SiO
₂
as back surface passivation layer. It was found that a 1-
$\mu \text{m}$
heavily doped thin p
⁺
layer was vital for improving the cell performances. Efficiency up to 12.7% with an open-circuit voltage of 679.7 mV was achieved on a 1.0-cm
$^{2}$
square cell. The device performance was also investigated by annealing at different temperatures. The results suggested that a relatively large thickness of a-Si:H and transparent conductive oxide layers could improve thermal stability of the solar cells at temperature above 300 °C.