TY - GEN
T1 - Ultrathin SiO2/Al2O3 passivation for silicon heterojunctions using rapid thermal annealing
AU - Kim, Sangpyeong
AU - Augusto, Andre
AU - Bowden, Stuart G.
AU - Honsbeg, Christiana B.
N1 - Publisher Copyright:
© 2020 IEEE.
PY - 2020/6/14
Y1 - 2020/6/14
N2 - In this manuscript we study the surface passivation properties of ultrathin Al2O3 in silicon heterojunctions. The Al2O3 layer needs to be thin enough (<1.2nm) to enable carrier collection through the passivation layer. Previous work on Al2O3 shows that thicknesses below 10nm do not provide adequate surface passivation. In this work, we combine 0.8 nm of Al2O3 with 1nm of SiO2 to improve the passivation properties of the thin Al2O3. The SiO2 helps to improve the chemical passivation by increasing the storage capacity of hydrogen with Al2O3, and the overall negative fixed charge of the SiO2/Al2O3 stack. Additionally, we have optimized the rapid thermal annealing in forming gas environment to activate the Al2O3 in the SiO2/Al2O3 stack. To further increase the hydrogen in the films we deposited n-a-Si:H film before the annealing step. Effective minority-carrier lifetimes of 5 ms and implied open-circuit voltages of 723 mV were accomplished.
AB - In this manuscript we study the surface passivation properties of ultrathin Al2O3 in silicon heterojunctions. The Al2O3 layer needs to be thin enough (<1.2nm) to enable carrier collection through the passivation layer. Previous work on Al2O3 shows that thicknesses below 10nm do not provide adequate surface passivation. In this work, we combine 0.8 nm of Al2O3 with 1nm of SiO2 to improve the passivation properties of the thin Al2O3. The SiO2 helps to improve the chemical passivation by increasing the storage capacity of hydrogen with Al2O3, and the overall negative fixed charge of the SiO2/Al2O3 stack. Additionally, we have optimized the rapid thermal annealing in forming gas environment to activate the Al2O3 in the SiO2/Al2O3 stack. To further increase the hydrogen in the films we deposited n-a-Si:H film before the annealing step. Effective minority-carrier lifetimes of 5 ms and implied open-circuit voltages of 723 mV were accomplished.
KW - Al2O3 passivation
KW - Rapid thermal annealing
KW - SiO2 inter layer
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U2 - 10.1109/PVSC45281.2020.9300895
DO - 10.1109/PVSC45281.2020.9300895
M3 - Conference contribution
AN - SCOPUS:85099552680
T3 - Conference Record of the IEEE Photovoltaic Specialists Conference
SP - 2104
EP - 2108
BT - 2020 47th IEEE Photovoltaic Specialists Conference, PVSC 2020
PB - Institute of Electrical and Electronics Engineers Inc.
T2 - 47th IEEE Photovoltaic Specialists Conference, PVSC 2020
Y2 - 15 June 2020 through 21 August 2020
ER -