Browsing by Author "Pande, Krishna"

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Gold-Free Fully Cu-Metallized InGaP/InGaAs/Ge Triple-Junction Solar Cells
(2014-12-01)
Hsu, Ching-Hsiang
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Chang, Edward Yi
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Chang, Hsun-Jui
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Yu, Hung-Wei
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Hong Quan Nguyen
Copper contacts and interconnects were developed for GaAs and Ge for low-cost solar cell application. In addition, thermally annealed Pd/Ge and Pt/Ti/Pt metallizations were created for ohmic contacts to n-GaAs and p-Ge with contact resistance of 4.4 x 10(-6) and 6.9 x 10(-6) Omega cm(2), respectively. Utilizing such metallization structure for InGaP/InGaAs/Ge triple-junction device structure solar cells were fabricated that delivered conversion efficiency of 23.11%, which is average efficiency for the above device structure.
Novel Low-Cost Power Divider for 5.8 GHz
(2020-04-01)
Chang, Tso-Jung
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Pande, Krishna
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Hsu, Heng-Tung
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國際半導體學院
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International College of Semiconductor Technology
This paper presents a new capacitive lump-free structure for power dividers using a printed-circuit board, while maintaining size reduction and physical isolation. The conventional lumped capacitors approach has self-resonant problem and cause worse S-22 and isolation at high frequencies. To overcome such technical issues, the coupled-line structures were introduced in the isolation network. After optimizing the distance between output ports and position of the isolation network, tuning the characteristic impedance and electrical length of transmission lines can decide the value of the lump resistor. The first example was designed at 1 GHz, and the resistor in the isolation network was 330 ohm, having 0.2-dB insertion loss and 19% total bandwidth, while maintaining 80-degree distance between split ports and 180-degree total length, providing 21% to 67% size reduction. The second example was designed at 5.8 GHz, which was five times greater than in past research, using an RO4003C substrate while maintaining a 0.24-dB insertion loss, 17% total bandwidth, and 0.06 dB amplitude imbalance, which was only 0.01 dB more than in recent research. Such superior performance is mainly attributed to the coupled transmission lines in the isolation network featuring a capacitive lump-free isolation network. Our data indicate that amplitude imbalance, bandwidth, and miniaturization are superior to any published data.
The reliability study of III-V solar cell with copper based contacts
(2015-12-01)
Hsu, Ching-Hsiang
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Chang, Edward Yi
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Chang, Hsun-Jui
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Maa, Jer-Shen
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Pande, Krishna
The reliability of III-V solar cell with copper based contacts as low-cost metallurgy option for solar cells including Cu-based Cu/Ge/Pd contact on n-type GaAs and Cu/Pt/Ti/Pt contact on p-type Ge is studied in this paper. The Cu-based contacts have low specific contact resistances of the order of 10(-6) Omega cm(2). The solar cells with the proposed Cu-based structures were subjected to high-temperature annealing (250 degrees C) and a high DC current (6.5 x 10(-4) mA/mu m(2)) stress test. Overall, the solar cell adopting these Cu-based contacts remained quite stable and demonstrated excellent performances after these reliability tests. (C) 2015 Elsevier Ltd. All rights reserved.