Study of GaInP solar-cell interfaces by variable-flux spectral measurements

The band structure and interface properties of solar cells based on GaInP/AlInP heterostructures are studied. The effect of band-structure variation at the interface between the $p$-AlInP wide-gap window and the $p$-GaInP emitter under the action of incident light is demonstrated. This effect results in the dependence of the spectral characteristics of GaInP solar cells on the irradiation intensity. A new procedure based on this effect is developed for estimating the minority carrier lifetime in the $p$-GaInP emitter layer and the density of surface states at the wide-gap window/emitter ($p$-AlInP/$p$-GaInP) interface. It is shown that the density of surface states at the $p$-AlInP/$p$-GaInP interface is within the range 10$^9$–10$^{11}$ cm$^{-2}$eV$^{-1}$.