Multiple morphologies and functionality of nanowires made from earth-abundant zinc phosphide

Abstract

Semiconductors made of earth-abundant elements, such as zinc phosphide, have the potential to substitute less abundant, highly functional compound semiconductors such as InAs or InP.

Showcasing the optical properties of monocrystalline zinc phosphide thin films as an earth-abundant photovoltaic absorber

“…Further studies should aim to more reliably separate surface and bulk effects with suitable surface treatments and to refine the identification of the specific defects involved in radiative recombination. The effect of the precise stoichiometry on the optical properties of thin films, in contrast to nanowires, 4,10 should also be studied in the future.…”

“…21 The lattice of zinc phosphide can accommodate relatively large compositional variations away from stoichiometry while maintaining the crystalline structure of Zn 3 P 2 . 10 The composition of our film across the depth, measured with Rutherford backscattering spectrometry (RBS), is shown in Fig. 2.…”

Measuring the Optical Absorption of Single Nanowires

“…Finally, we measure the absorption in a Zn 3 P 2 superlattice NW. Owing to its strong absorption in the visible range and earth abundancy, Zn 3 P 2 is a promising material for photovoltaics, which has recently been grown epitaxially in the NW form [35]. Our measurements testify its great capability to absorb light.…”

“…Furthermore, the absorptance has only weak dependence on the energy within the measured energy range. This is expected since the measurements are taking place far beyond the band-gap energy [35,36]. The highest absorption, for both polarization configurations, is found at around 2.2 eV, which could be due to an electronic resonance, since theoretical studies predict a transition around this energy level [55].…”

“…Our measurements testify its great capability to absorb light. In bulk an indirect band gap has been measured at 1.38 eV and a direct band gap at 1.5 eV [36], while a transition at 1.43 eV has been measured using CL measurements [35], so all our measurements are at an energy far beyond the band gap, but in the interesting range for photovoltaic applications.…”