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 films 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 film, 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 film. 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 field of an 80-nm Al2O3 film are 5.46 × 1014 Ω-cm and 3.28 MV/cm, respectively, which are stable after 800°C firing. These properties suggest that spray-deposited Al2O3 is a promising candidate to replace the Al2O3/SiNx stack in Si PERC cells.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials