GaAs nanopillar-array solar cells employing in situ surface passivation

Abstract

Arrays of III–V direct-bandgap semiconductor nanopillars represent promising photovoltaic candidates due to their inherent high optical absorption coefficients and minimized reflection arising from light trapping, efficient charge collection in the radial direction and the ability to synthesize them on low-cost platforms. However, the increased surface area results in surface states that hamper the power conversion efficiency. Here, we report the first demonstration of GaAs nanopillar-array photovoltaics employing epitaxial passivation with air mass 1.5 global power conversion efficiencies of 6.63%. High-bandgap epitaxial InGaP shells are grown in situ and cap the radial p–n junctions to alleviate surface-state effects. Under light, the photovoltaic devices exhibit open-circuit voltages of 0.44 V, short-circuit current densities of 24.3 mA cm−2 and fill factors of 62% with high external quantum efficiencies >70% across the spectral regime of interest. A novel titanium/indium tin oxide annealed alloy is exploited as transparent ohmic anode.

Lasing from individual GaAs-AlGaAs core-shell nanowires up to room temperature

“…To date, only a few works report lasing from electrically excited NWs 4,43 . However, radial p-n junctions in GaAs-based NWs exist driven mostly by potential applications in NW photovoltaics 44 . The availability of such materials provides much promise for the future development of electrically driven, compact III/V NW-laser sources grown site selectively on silicon photonic hardware with the potential for NWs to make a breakthrough in the development of optical interconnects.…”

Nanophotonic integrated circuits from nanoresonators grown on silicon

“…While SiO 2 offers remarkable surface passivation properties for silicon 10 , a comparable solution for III-V semiconductors remains absent. On the other hand, low-defect single-crystal nanostructures can be grown with atomically flat surfaces and in situ surface passivation via higher band gap cladding layers 11,12 , which have historically proven to provide the best passivation for III-V materials. With tiny footprints, nanostructures incur minimal real estate cost while offering full photonic functionality.…”

Effect of catalyst diameter on vapour-liquid-solid growth of GaAs nanowires

“…The interesting structural, electronic and optical properties of free-standing III-V nanowires have generated significant interest and inspired the design of a wide variety of proposed applications [1][2][3][4][5] . The Vapour-Liquid-Solid (VLS) mechanism is widely used to fabricate…”