3:30 PM - 4:00 PM
▲ [13p-4F-5] Passivation of crystalline silicon with solution-processed amorphous silicon
Keywords:amorphous silicon,liquid semiconductor precursor,solar cells
This contribution aims at investigating the conversion from Neopentasilane to amorphous silicon (a-Si:H) and at evaluating the potential of solution processed a-Si:H layers for surface passivation of crystalline silicon.
Liquid silicon precursors based on Neopentasilane were prepared and converted to a-Si:H using spin-coating and subsequent annealing.
To further decrease the defect density in the a-Si:H layers and at the a-Si:H/c-Si interface hydrogen plasma post-deposition treatments were applied.
The annealing temperature for the conversion from liquid Neopentasilane to a-Si:H was varied from 250°C to 600°C and the passivation properties of the layers were investigated using carrier lifetime spectroscopy. The thermally treated layers exhibit strong charge induced and unstable passivation if the annealing temperature is kept below 350°C. For annealing temperatures above 400°C the layers are fully converted to a-Si:H and the passivation is due to chemical passivation of dangling bonds.
A hydrogen plasma and in diffusion of hydrogen to the a-Si:H/c-Si interface can greatly enhance the passivation and enables excellent minority carrier lifetimes of 1.37 milliseconds.
Furthermore the electronic properties of spin-coated a-Si:H are compared to state of the art a-Si:H deposited using plasma-enhanced chemical vapor deposition. The liquid processed layers exhibit Urbach energies of 90 to 120 meV, compared to about 60 meV for PECV deposited a-Si:H. Furthermore their valence band is about 200 meV closer to the Fermi level, since the exhibit lower hydrogen contents.
Nevertheless the excellent minority carrier lifetime of about 1.37 milliseconds enables an implied open circuit voltage of about 724 mV and proves the viability of the presented approach.
Liquid silicon precursors based on Neopentasilane were prepared and converted to a-Si:H using spin-coating and subsequent annealing.
To further decrease the defect density in the a-Si:H layers and at the a-Si:H/c-Si interface hydrogen plasma post-deposition treatments were applied.
The annealing temperature for the conversion from liquid Neopentasilane to a-Si:H was varied from 250°C to 600°C and the passivation properties of the layers were investigated using carrier lifetime spectroscopy. The thermally treated layers exhibit strong charge induced and unstable passivation if the annealing temperature is kept below 350°C. For annealing temperatures above 400°C the layers are fully converted to a-Si:H and the passivation is due to chemical passivation of dangling bonds.
A hydrogen plasma and in diffusion of hydrogen to the a-Si:H/c-Si interface can greatly enhance the passivation and enables excellent minority carrier lifetimes of 1.37 milliseconds.
Furthermore the electronic properties of spin-coated a-Si:H are compared to state of the art a-Si:H deposited using plasma-enhanced chemical vapor deposition. The liquid processed layers exhibit Urbach energies of 90 to 120 meV, compared to about 60 meV for PECV deposited a-Si:H. Furthermore their valence band is about 200 meV closer to the Fermi level, since the exhibit lower hydrogen contents.
Nevertheless the excellent minority carrier lifetime of about 1.37 milliseconds enables an implied open circuit voltage of about 724 mV and proves the viability of the presented approach.