A Comparative Study of Absorption in Vertically and Laterally Oriented InP Core–Shell Nanowire Photovoltaic Devices

Abstract

We have compared the absorption in InP core-shell nanowire p-i-n junctions in lateral and vertical orientation. Arrays of vertical core-shell nanowires with 400 nm pitch and 280 nm diameter, as well as corresponding lateral single core-shell nanowires, were configured as photovoltaic devices. The photovoltaic characteristics of the samples, measured under 1 sun illumination, showed a higher absorption in lateral single nanowires compared to that in individual vertical nanowires, arranged in arrays with 400 nm pitch. Electromagnetic modeling of the structures confirmed the experimental observations and showed that the absorption in a vertical nanowire in an array depends strongly on the array pitch. The modeling demonstrated that, depending on the array pitch, absorption in a vertical nanowire can be lower or higher than that in a lateral nanowire with equal absorption predicted at a pitch of 510 nm for our nanowire geometry. The technology described in this Letter facilitates quantitative comparison of absorption in laterally and vertically oriented core-shell nanowire p-i-n junctions and can aid in the design, optimization, and performance evaluation of nanowire-based core-shell photovoltaic devices.

Design for strong absorption in a nanowire array tandem solar cell

“…It is known that the nanowire diameter affects strongly the absorption of light15781335. Therefore, to study the effect of the nanowire diameter on the absorption in the tandem cell, we fix P  = 530 nm, L top  = 2000 nm, and L bot  = 2900 nm [Fig.…”

“…Both single wire467 and large-area nanowire array589 devices show promise for next generation solar cells. Already for single nanowire systems, diffraction of light can lead to resonant coupling of light into the nanowire with several absorption peaks as a function of wavelength1011.…”

Strategies to obtain pattern fidelity in nanowire growth from large-area surfaces patterned using nanoimprint lithography

“…A growth mask of either SiNx or SiOx is commonly used in catalyst-free selective area NW growth [32,33], and in self-catalyzed NW growth [34,35]. A growth mask has been successfully used for metal-catalyzed Si microwires [36,37] and III-V NW growth [38][39][40]. We used a SiNx growth mask, and achieved 100% preservation of the pattern for grown NWs over all sampled areas (see the ESM).…”

Nanowires for High-Efficiency, Low-Cost Solar Photovoltaics

“…It also needs to be mentioned that the solar cells with good efficiencies are achieved with axial p-i-n junctions. The efficiency of those with radial p-i-n junctions is still lower than 7.5% [95,96,114,[120][121][122][123][124][125][126]. This could be because it is relatively difficult to fabricate the contact on a radial junction.…”