Optimization of InGaN/GaN heterostructure solar cell with incorporation of GaN interlayer

The III-Nitride material system offers significant potential in developing high efficiency solar cells (SC) due to their tunable bandgap (0.7 eV- 3.42 eV) with varying indium (In) concentration. Few characteristics of InGaN include wide and direct bandgap (E_g), high absorption coefficient (10⁵ cm^-1) and longer lifetimes. In this paper, InGaN/GaN SC with incorporation of GaN interlayers in absorber layer with an In content of 0.10 has been modeled and studied. InGaN is used as absorber, whereas GaN is used as window layers and strain reducing layer within the absorber layer. Increased P-GaN layer thickness increases short circuit current density (J_sc) to 2.5 mAcm^-2, but lowers the open circuit voltage (V_oc) to 2.11 V. GaN layer is taken to be thin enough to allow tunneling between InGaN layers and thick enough to be effective. Increase in GaN thickness increases V_oc and decreases J_sc. J_sc is higher for smaller thickness of InGaN whereas V_oc is higher for thicker absorber layer. The n-GaN layer thickness does not play important role in absorption of carrier. The V_oc and J_sc of the device are 2.52 V and 0.653 mAcm^-2, respectively.