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

Abstract

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.