  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.
