Address: Nanofabrication for optoelectronic applications INL- International Iberian Nanotechnology Laboratory Avenida Mestre José Veiga 4715-330 Braga Portugal
Ultrathin Cu(In,Ga)Se2 solar cells are a promising way to reduce costs and to increase the electr... more Ultrathin Cu(In,Ga)Se2 solar cells are a promising way to reduce costs and to increase the electrical performance of thin film solar cells. In this work, we develop an optical lithography process that can produce sub-micrometer contacts in a SiO2 passivation layer at the CIGS rear contact. Furthermore, an optimization of the patterning dimensions reveals constrains over the features sizes. High passivation areas of the rear contact are needed to passivate the CIGS interface so that high performing solar cells can be obtained. However, these dimensions should not be achieved by using long distances between the contacts as they lead to poor electrical performance due to poor carrier extraction. This study expands the choice of passivation materials already known for ultrathin solar cells and its fabrication techniques.
— In this work, Metal-Insulator-Semiconductor (MIS) structures were fabricated in order to study ... more — In this work, Metal-Insulator-Semiconductor (MIS) structures were fabricated in order to study different types of insulators, namely, aluminum oxide (Al 2 O 3), silicon nitride (Si 3Nx) and silicon oxide (SiO x) to be used as passivation layers in Cu(In,Ga)Se 2 (CIGS) thin film solar cells. The investigated stacks consisted of SLG/Mo/CIGS/insulator/Al. Raman scattering and Photoluminescence measurements were done to verify the insulator deposition influence on the CIGS surface. In order to study the electrical properties of the CIGS-insulator interface, capacitance vs. conductance and voltage (C-G-V) measurements were done to estimate the number and polarity of fixed insulator charges (Q f). The density of interface defects (D it) was estimated from capacitance vs. conductance and frequency (C-G-f) measurements. This study evidences that the deposition of the insulators at high temperatures (300 ºC) and the use of sputtering technique cause surface modification on the CIGS surface. We found that, by varying the SiO x deposition parameters, it is possible to have opposite charges inside the insulator, which would allow its use in different device architectures. The material with lower D it values was Al 2 O 3 when deposited by sputtering.
Ultrathin Cu(In,Ga)Se2 solar cells are a promising way to reduce costs and to increase the electr... more Ultrathin Cu(In,Ga)Se2 solar cells are a promising way to reduce costs and to increase the electrical performance of thin film solar cells. In this work, we develop an optical lithography process that can produce sub-micrometer contacts in a SiO2 passivation layer at the CIGS rear contact. Furthermore, an optimization of the patterning dimensions reveals constrains over the features sizes. High passivation areas of the rear contact are needed to passivate the CIGS interface so that high performing solar cells can be obtained. However, these dimensions should not be achieved by using long distances between the contacts as they lead to poor electrical performance due to poor carrier extraction. This study expands the choice of passivation materials already known for ultrathin solar cells and its fabrication techniques.
— In this work, Metal-Insulator-Semiconductor (MIS) structures were fabricated in order to study ... more — In this work, Metal-Insulator-Semiconductor (MIS) structures were fabricated in order to study different types of insulators, namely, aluminum oxide (Al 2 O 3), silicon nitride (Si 3Nx) and silicon oxide (SiO x) to be used as passivation layers in Cu(In,Ga)Se 2 (CIGS) thin film solar cells. The investigated stacks consisted of SLG/Mo/CIGS/insulator/Al. Raman scattering and Photoluminescence measurements were done to verify the insulator deposition influence on the CIGS surface. In order to study the electrical properties of the CIGS-insulator interface, capacitance vs. conductance and voltage (C-G-V) measurements were done to estimate the number and polarity of fixed insulator charges (Q f). The density of interface defects (D it) was estimated from capacitance vs. conductance and frequency (C-G-f) measurements. This study evidences that the deposition of the insulators at high temperatures (300 ºC) and the use of sputtering technique cause surface modification on the CIGS surface. We found that, by varying the SiO x deposition parameters, it is possible to have opposite charges inside the insulator, which would allow its use in different device architectures. The material with lower D it values was Al 2 O 3 when deposited by sputtering.
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Papers by José M . V . Cunha