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
${\rm In}=21\%$
and 40% in InGaN multiple quantum wells, and
${\rm Al}=14\%$
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
$({\rm hole~concentration}=3\times 10^{17}~{\rm cm}^{-3})~{\rm Al}_{0.2}{\rm Ga}_{0.8}{\rm N}$
barriers in
${\rm In}_{0.4}{\rm Ga}_{0.6}{\rm N}$
superlattice solar cell when compared with undoped
${\rm Al}_{0.14}{\rm Ga}_{0.86}{\rm N}$
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.