Beschreibung:
The presence of silicon oxyphosphide in the heavily phosphorus-doped n + -type polycrystalline silicon film (poly Si) of TOPCon solar cell has been mainly revealed through a depth-profile X-ray photoelectron spectroscopy (XPS) characterization of chemical components. X-ray diffraction (XRD) pattern is applied to the verification of compositional phases in the n + -poly-Si film, while high-resolution transmission electron microscopy (HR-TEM) with energy dispersive X-ray (EDX) pattern is used for distinguishing the crystallinity and the elemental segregation. The test sample is of a typical rear passivation contact stacks of c-Si/SiO x /n + -poly Si/SiO 2 , in which the n + -poly Si layer is heavily phosphorus-doped by ion implantation of as deposited intrinsic thin film through low pressure chemical vapor deposition (LPCVD) and recrystallization at 900 °C afterwards. In the whole n + -poly Si layer, XPS P 2p electronic states at 129.79, 133.42 and 136.77 eV have been detected and assigned to be Si-P (or P-P), O-P and P-O-P bonds, respectively. In addition, the thermodynamic analyses of equilibrium state and Gibbs free energy as well as temperature-composition fraction (T-CF) phase diagram are also implemented to the verification of the derivatives of phosphorus oxides