InP nanowire array solar cells
Q. Gao, L. Fu, Z. Li, Y. C. Wenas, F. Wang, Li Li, Z. Y. Li, S. Mokkapati, H. H. Tan
and C. Jagadish
Department of Electronic Materials Engineering, Research School of Physics and
Engineering,The Australian National University, Canberra, ACT 0200, Australia
Email: ful109@physics.anu.edu.au
Semiconductor nanowires have received increasing attention in recent years as
building blocks for nanodevices, such as LEDs, lasers, photodetectors and solar
cells. In particular for solar cell applications, nanowires are of great interest because
of (i) the large surface area, (ii) high aspect ratio (iii) intrinsic antireflection effect that
increases light absorption and (iv) the ability to form well aligned arrays. More
importantly, they provide a paradigm shift in photovoltaics by decoupling light
absorption from carrier collection paths through the radial pn junction geometry,
which could lead to more efficient charge extraction. By incorporating the superior
photovoltaic properties of III-V semiconductors into nanowire structures, it is
expected that further enhancement in the solar cell efficiency can be achieved with
significant cost reduction due to much less material usage in nanowires.
Compared with the commonly used vapour-liquid-solid (VLS) mechanism for NW
growth, catalyst-free, selective area epitaxy (SAE) is highly desirable, since the
position, geometry, uniformity and doping of NWs can be more accurately controlled
and thus optimized to improve the solar cell performance. In this work, we will
present our recent progress in the development of InP nanowire array solar cells,
including growth of high quality SAE InP nanowire arrays by metalorganic chemical
vapour deposition (MOCVD), combined optical and electrical numerical simulation to
optimize the array and junction design, as well as new fabrication and
characterization techniques for high performance nanowire array solar cell
applications.
We acknowledge the Australian Research Council (ARC) for financial support, and
the Australian National Fabrication Facility (ANFF) ACT node for facility support. We
thank ANFF staff Drs. Kaushal Vora, and Fouad Karouta for useful discussions.