Title :
Development of low-bandgap Ge and Si0.07Ge0.93 solar cells for monolithic and mechanically-stacked cascade applications
Author :
Venkatasubramanian, R. ; Timmons, M. ; Pickett, R. ; Colpitts, T. ; Hils, J.S. ; Hutchby, J.A. ; Hes, P.A. ; Chu, C.L.
Author_Institution :
Res. Triangle Inst., Research Triangle Park, NC, USA
Abstract :
Ge and Si0.07Ge0.93 materials are suitable for cascade solar cell applications in tandem with ~1.6 eV top cells in 1- and 100-sun space photovoltaic arrays. Ge homojunction cell performance, measured undo Spectrolab XT-10 and Hoffman simulators, is presented. Short-circuit current densities of as much as 70.5 mA/cm2 have been measured under the XT-10, suggesting excellent photocollection from the epitaxially grown Ge structures. Ge homojunction cells show substantial improvement with the incorporation of a p+-Al0.85Ga0.15As indirect-gap layer as front-surface ·passivation. The photovoltaic characteristics of Si0.07Ge0.93 cells are also presented. Jsc values of 62.3 mA/cm2 have been measured in these cells under the XT-10. Open-circuit voltages in Ge and SiGe cells are in the range of 0.21 V and 0.18 V respectively. Spectral-response measurements on the cells are presented, and future directions for improving the cells are suggested
Keywords :
Ge-Si alloys; elemental semiconductors; germanium; solar cells; space vehicle power plants; ·passivation; 0.21 to 0.18 V; 1.6 eV; Al0.85Ga0.15As; Ge-Si0.07Ge0.93; cascade; epitaxial growth; homojunction; open-circuit voltage; performance; photocollection; short-circuit currents; solar cells; space photovoltaic arrays; tandem; top cells; Building integrated photovoltaics; Current density; Current measurement; Density measurement; Germanium silicon alloys; Photovoltaic cells; Photovoltaic systems; Silicon germanium; Solar power generation; Voltage;
Conference_Titel :
Photovoltaic Specialists Conference, 1990., Conference Record of the Twenty First IEEE
Conference_Location :
Kissimmee, FL
DOI :
10.1109/PVSC.1990.111594
