Measuring, controlling and exploiting heterogeneity in optoelectronic nanowires

Abstract

Fabricated from ZnO, III-N, chalcogenide-based, III-V, hybrid perovskite or other materials, semiconductor nanowires offer single-element and array functionality as photovoltaic, non-linear, electroluminescent and lasing components. In many applications their advantageous properties emerge from their geometry; a high surface-to-volume ratio for facile access to carriers, wavelength-scale dimensions for waveguiding or a small nanowire-substrate footprint enabling heterogeneous growth. However, inhomogeneity during bottom-up growth is ubiquitous and can impact morphology, geometry, crystal structure, defect density, heterostructure dimensions and ultimately functional performance. In this topical review, we discuss the origin and impact of heterogeneity within and between optoelectronic nanowires, and introduce methods to assess, optimise and ultimately exploit wire-to-wire disorder.

Improving Quantum Well Tube Homogeneity Using Strained Nanowire Heterostructures

“…However, the relative impact of inter-and intrawire inhomogeneity is dependent on the intended application. 6 Crucially for nanowire lasing, the optimization of the diameter for the transverse mode strongly influences the lasing threshold and the interwire diameter inhomogeneity will directly impact the lasing yield. 50,51 For the presented material, the average spread in diameter across each slice is 106 nm (19% of the nominal median); this compares to 122 nm (22%) across the whole population.…”

“…3 While planar heterostructure growth has been optimized for decades, 4 heterostructured bottom-up grown materials such as nanowires 5 (NWs) are less well controlled due to the complex interplay between local growth environment, a narrow growth window, and a stochastic seeding process. 6 Optoelectronically homogeneous and defectfree NWs are desired for photonic integrated circuits 7−9 where material quality has been shown to impact electron mobility 10 and in photovoltaic cells 3,11−14 where improved homogeneity directly correlates to total device efficiency and functional yield. 15 Radial quantum well (QW) heterostructures are one particular candidate for these applications due to ease of tunability and a demonstrated compatibility with highly strained systems.…”

“…There is a demand for faster, denser, and increasingly efficient optoelectronic devices for use in next generation optoelectronic devices such as telecommunications , and energy harvesting applications . While planar heterostructure growth has been optimized for decades, heterostructured bottom-up grown materials such as nanowires (NWs) are less well controlled due to the complex interplay between local growth environment, a narrow growth window, and a stochastic seeding process . Optoelectronically homogeneous and defect-free NWs are desired for photonic integrated circuits − where material quality has been shown to impact electron mobility and in photovoltaic cells ,− where improved homogeneity directly correlates to total device efficiency and functional yield .…”

Holistic Nanowire Laser Characterization as a Route to Optimal Design

“…For both vapor‐liquid solid (VLS) and selective area growth (SAE) NWs there is an additional complication: since the growth is driven by thermodynamic processes, the NWs demonstrate variation in material and cavity properties that influence the lasing performance. [ 21 ] It is therefore difficult to vary a single property in isolation, which makes any systematic study of these effects a challenge.…”

Sub-Picosecond Carrier Dynamics Explored using Automated High-Throughput Studies of Doping Inhomogeneity within a Bayesian Framework

“…1 However, this capability is tempered by the sensitivity of growth to local conditions, and variation in precursor concentration, ratio, or temperature can lead to significant variation in yield or functional performance. 2 Crucially, both ensemble and single-element characterisation are highly challenging for nanomaterials, creating a bottleneck for their exploitation; the former as it cannot measure inhomogeneity and the latter because measurement of a local region may not represent the whole sample size. 3 GaAs nanowires (NWs) have been widely studied for optoelectronic applications; [4][5][6][7][8] they can be produced with high crystal quality 9,10 and provide a facile route to heterostructure design based on decades of experience in planar material growth.…”