Patterned germanium tunnel junctions for multijunction monolithic cascade solar cells

• Published in: Solar cells Vol. 21; no. 1; pp. 241 - 252
• Main Authors: Chiang, P.K, Timmons, M.L, Hutchby, J.A
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Lausanne Elsevier B.V 01.06.1987; Elsevier Sequoia
• Subjects: Applied sciences; Energy; Exact sciences and technology; Natural energy; Solar energy; Solar thermal conversion; Solar cell; Germanium; Tunnel junction; Interconnection; Multijunction structure; Solar energy
• ISSN: 0379-6787; 1878-2655
• DOI: 10.1016/0379-6787(87)90124-4

The growth and characterization of germanium interconnects is described in this paper. Resistivity measurements indicate that n +-GaAs/p +-Ge/p +-GaAs structures may be the most viable interconnect yet reported for monolithic cascade cells. Specific interface resistivities as low as 1 × 10 −4 Ω cm 2 have been measured. This value surpasses the goal of 1.7 × 10 −4 Ω cm 2 for a cascade cell with a patterned interconnect operating at 1000 Suns under air mass 1.5 conditions. To pattern germanium layers, both wet chemical etching and selective epitaxial growth have been used. Excellent germanium interconnecting patterns have been reproducibly achieved using selective epitaxy. Using the patterned germanium interconnects, cascade action has been unambiguously observed in the AlGaAs/GaAs multijunction cascade solar cells.