Advantages of InGaN Solar Cells With p-Doped and High-Al-Content Superlattice AlGaN Barriers

In this letter, the photovoltaic characteristics of InGaN/AlGaN superlattice solar cells with In=21% and 40% in InGaN multiple quantum wells, and Al=14% and 20% in AlGaN barriers are investigated. The results obtained numerically show that an increment of 18.2% in short-circuit current density is achieved by introducing p-type doped (hole concentration = 3×10¹⁷ cm^-3) Al_0.2Ga_0.8N barriers in In_0.4Ga_0.6N superlattice solar cell when compared with undoped Al_0.14Ga_0.86N barriers. This improvement is mainly attributed to the increased electric field in the main absorption region, which is beneficial for the holes in the valence band to move towards the p-region. The capability of carrier transport is efficiently improved, thus increasing the carrier-collection efficiency and the conversion efficiency.