Spray-Deposited Al <sub/>2</sub> O <sub/>3</sub> for Rear Passivation and Optical Trapping in Silicon Solar Cells

摘要： Low-cost spray deposition is employed to investigate the suitability of spray-deposited Al2O3 for rear passivation and optical trapping in passivated emitter rear contact (PERC) Si solar cells. Structural, optical, and electrical properties of spray-deposited Al2O3 ?lms are investigated. Capacitance-voltage measurements indicate that spray-deposited Al2O3 has a negative charge density of 3.19 × 1012 cm–2 for an 80-nm ?lm, suggesting that it can serve as the passivation layer. Optical properties of spray-deposited Al2O3 are identical to the Al2O3/SiNx stack prepared by atomic layer deposition and plasma-enhanced chemical vapor deposition, indicating that it can also serve as the optical trapping layer. Atomic force microscopy studies show that spray-deposited Al2O3 is crack and pore free, and its surface roughness has a root-mean-square value of 0.52 nm for an 80-nm ?lm. Spray-deposited Al2O3 is amorphous as determined by X-ray diffraction. X-ray photoelectron spectroscopy analysis suggests that spray-deposited Al2O3 is slightly Al-rich. The resistivity and breakdown ?eld of an 80-nm Al2O3 ?lm are 5.46 × 1014 Ω-cm and 3.28 MV/cm, respectively, which are stable after 800°C ?ring. These properties suggest that spray-deposited Al2O3 is a promising candidate to replace the Al2O3/SiNx stack in Si PERC cells.