Influence of the AlN interlayer thickness on the photovoltaic properties of In-rich AlInN on Si heterojunctions deposited by RF sputtering

TL;DR

This study investigates how varying the AlN interlayer thickness affects the photovoltaic performance of In-rich AlInN/Si heterojunction solar cells, highlighting the importance of interface quality and buffer layer optimization.

Contribution

It demonstrates that a 4-nm AlN buffer layer enhances crystalline quality and efficiency of AlInN/Si solar cells deposited by RF sputtering, showing potential for novel electron-selective contacts.

Findings

Optimal AlN thickness improves device efficiency to 1.5%.

Thicker buffers reduce performance due to tunnel transport issues.

Interface quality critically affects photovoltaic response.

Abstract

We report the influence of the AlN interlayer thickness (0-15 nm) on the photovoltaic properties of Al0.37In0.63N on Si heterojunction solar cells deposited by radio frequency sputtering. The poor junction band alignment and the presence of a 2-3 nm thick amorphous layer at the interface mitigates the response in devices fabricated by direct deposition of n-AlInN on p-Si(111). Adding a 4-nm-thick AlN buffer layer improves the AlInN crystalline quality and the interface alignment leading to devices with a conversion efficiency of 1.5% under 1-sun AM1.5G illumination. For thicker buffers the performance lessens due to inefficient tunnel transport through the AlN. These results demonstrate the feasibility of using In-rich AlInN alloys deposited by radio frequency sputtering as novel electron-selective contacts to Si-heterojunction solar cells.