Numerical Simulation of Single-Junction In$_{0.5}$Ga$_{0.5}$P Solar Cell With Compositional Grading Configuration

A compositional grading layer between the p-In
_0.5
Ga
_0.5
P emitter layer and p-In
_0.5
Al
_0.5
P window layer in the p
⁺
-n In
_0.5
Ga
_0.5
P solar cell is investigated numerically. With the insertion of the grading layer, the short-circuit current density and conversion efficiency are improved due to the enhancement of carrier-collection efficiency, which can be ascribed to the reduction of potential barrier height in the valance band and the existence of internal quasi-electric field in the conduction band. An optimized value of conversion efficiency can be obtained by appropriately adjusting the thickness of the grading layer.