GaAS one-sun and concentrator solar cells based on LPE-ER grown structures
The liquid-phase epitaxy etchback regrowth (LPE-ER) technique was used to grow AlGaAs/GaAs heteroface and AlGaAs/AlyGa1-y As(0.1<y<0.3) heteroface solar cell structures. The influence of substrate position (vertical or horizontal) during the LPE-ER process was investigated. A model for the growth of the LPE-ER structure in vertical substrate position is proposed. The LPE-ER grown structures were used to fabricate one-sun and concentrator solar cells. Efficiencies of up to 22.4% (AM1.5G) were achieved for solar cells of 4 cm2 area. For concentrator application an efficiency of 24.8% (AM1.5, direct) was measured at 105 suns on a 13 mm2 solar cell. A 243 cm2 aperture area concentrator module consisting of 12 Fresnel lenses and 12 LPE-ER grown GaAs solar cells showed an efficiency of 20.3% under outdoor conditions.