Adjusting the conductivity of GaInNAs solar cells from p- to n-type with the As/III ratio

In this work, we report on the growth of p-i-n dilute nitride solar cells with highly compensated GaInNAs (1.0 eV bandgap) layers. We obtained internal quantum efficiencies (IQE) up to 85 % at 0.2 eV above the bandgap. The compensation doping was achieved by the formation of n-type defects during the GaInNAs growth. We were able to fine tune the concentration of the n-type defects by the As/III ratio in a range wide enough to continuously adjust the GaInNAs layer from p-type to n-type. However, the high IQE comes along with an increased dark current density, resulting in a decreased open circuit voltage (VOC) of about 0.2 V.