High-efficiency GaAs/Ge monolithic tandem solar cells

Quantum yield spectra and I-V properties of a GaAs solar cell grown on a Ge substrate

“…Tobin et a1 (6) have proposed that a p/n junction is formed inside the Ge substrate near its interface with the GaAs due to the differing solubilities and diffusion coefficients of Ga and As that act as p and n type dopants in Ge respectively (24). They identified such a region in their early work (6) using a spreading resistance probe, but their latest, hi h efficiency device (2) showed only a trace of a 8;e p layer. Presumably this top most p-Ge layer would also be highly enough doped to form an interconnecting tunnel junction to the overlying n GaAs doped even more n type (24) by Ge diffusion.…”

“…Growth of GaAs solar cells on Ge substrates offers the potential advantages of combining the high efficiency and radiation resistance of GaAs cells with the strong mechanical properties of Ge so that thin, light weight substrates can be used (1,2). Initial work on this structure gave efficiencies up to 21 YO AMI using p-Ge substrates and sequential growth of a p-GaAs layer followed by a thin n+-GaAs but no heteroface AlGaAs window passivation (3).…”

Heteroepitaxial Growth of GaAs/Ge Buffer Layer on Si for Metamorphic InGaAs Lasers

“…Moreover, GaAs layers on Ge have also been widely studied. GaAs-on-Ge-based high-efficiency photovoltaics for space applications have been developed [13], [14]. Furthermore, several research groups have developed laser diodes Manuscript received November 2, 2017.…”

(Invited) Group-IV Subcells in Multijunction Concentrator Solar Cells

“…Germanium photovoltaic cells have been used in combination with III-V subcells in highefficiency multijunction solar cells for many years (1)(2)(3). Three-junction GaInP/ Ga(In)As/ Ge solar cells with an active Ge bottom subcell have been the highest efficiency commercially available solar cells for space applications since 2000, and for terrestrial concentrator photovoltaic (CPV) applications since 2001.…”