Characteristics of InGaN/sapphire-based photovoltaic devices with different superlattice absorption layers and buffer layers

In this study, hetero-structure p-i-n type epitaxy wafers were deposited on the GaN/sapphire templates with different buffer layers by the MOVPE system. The absorption layers sandwiched in top p-GaN and bottom n+-GaN layers were designed into different short-period InGaN/GaN superlattice structures with specific pair numbers to maintain a total absorption thickness of 200 nm. As the buffer layer was properly adjusted, the VOC and JSC were enhanced by 35% and 95%, respectively. In addition to material qualities, the thickness of GaN buffer layers and piezoelectric-induced stain in the InGaN film itself also influenced the PV device performance.