III-phosphides heterojunction solar cell interface properties from admittance spectroscopy

GaInP solar cell interfaces were characterized by admittance spectroscopy. Admittance spectroscopy is shown to be sensitive to the band structure at the heterojunction interfaces. In particular, a correlation between activation energy of the capacitance step in a capacitance versus temperature plot and effective potential barrier for majority carriers is demonstrated, indicating a new method for the determination of potential barriers at heterointerfaces. Using this technique, the effective potential barrier for holes at the p-Al0.53In0.47P/p-GaAs interface is found to be equal to 0.6 eV. Effects of interface defects and spreading resistance in the emitter of solar cells are illustrated and discussed.