The stability of illuminated p-GaInP2 semiconductor photoelectrode

Thin p-GaInP₂ films were tested 24 h in pH1 NH₄NO₃ solution at AM 1.5 G, and compared to that tested in 3 M H₂SO₄. Optical, SEM and EDX investigations confirmed that the surface of the tested sample in pH1 NH₄NO₃ was kept almost as that of an as-received one, while the sample tested in 3 M H₂SO₄ experienced extensive corrosion via selective dissolution of Ga. ICP analysis confirmed the very low dissolution of p-GaInP₂ in pH1 NH₄NO₃ solution, compared to that in 3 M H₂SO₄. The GaInP₂ sample tested in pH1 NH₄NO₃ solution had an XPS depth profile almost identical to that of an as-grown sample, we speculate that absorbed NH₃ on the semiconductor surface could be responsible for the observed corrosion inhibition. Thus, the p-GaInP₂ should last much longer when working in pH1 NH₄NO₃ solution, due to this inhibiting effect. This result shows promise toward meeting US DOE's 2013 goal of 8% STH efficiency for 1000 h duration.