Understanding the Anisotropy in the Electrical Conductivity of CuPt-type Ordered GaInP Thin Films by Combining TEM Biasing and First Principles Calculations.

In this work, the effect of CuPt ordering on the optoelectronic properties of GaInP is studied by combining transmission electron microscopy measurements and density functional theory (DFT) calculations. GaInP layers were grown by metal organic vapor phase epitaxy with a CuPt single-variant-induced ordering due to the intentional misorientation of the Ge(001) substrate. Moreover, the degree of order was controlled using Sb as the surfactant without changing other growth parameters.

Photovoltaic nanowires affect human lung cell proliferation under illumination conditions.

Using light to interact with cells is a promising way to steer cell behavior with minimal perturbation. Besides optogenetics, photovoltaic nanostructures such as nanowires can be used to interact with cells using light as a switch. Photovoltaic nanowires have, for instance, been used to stimulate neurons.

Hot-carrier separation in heterostructure nanowires observed by electron-beam induced current.

The separation of hot carriers in semiconductors is of interest for applications such as thermovoltaic photodetection and third-generation photovoltaics. Semiconductor nanowires offer several potential advantages for effective hot-carrier separation such as: a high degree of control and flexibility in heterostructure-based band engineering, increased hot-carrier temperatures compared to bulk, and a geometry well suited for local control of light absorption. Indeed, InAs nanowires with a short InP energy barrier have been observed to produce electric power under global illumination, with an open-circuit voltage exceeding the Shockley-Queisser limit.

Template-assisted vapour-liquid-solid growth of InP nanowires on (001) InP and Si substrates.

We report on the synthesis of vertical InP nanowire arrays on (001) InP and Si substrates using template-assisted vapour-liquid-solid growth. A thick silicon oxide layer was first deposited on the substrates. The samples were then patterned by electron beam lithography and deep dry etching through the oxide layer down to the substrate surface.

Synthesis and Applications of III-V Nanowires.

Low-dimensional semiconductor materials structures, where nanowires are needle-like one-dimensional examples, have developed into one of the most intensely studied fields of science and technology. The subarea described in this review is compound semiconductor nanowires, with the materials covered limited to III-V materials (like GaAs, InAs, GaP, InP,..

Three-Dimensional Imaging of Beam-Induced Biasing of InP/GaInP Tunnel Diodes.

Electron holographic tomography was used to obtain three-dimensional reconstructions of the morphology and electrostatic potential gradient of axial GaInP/InP nanowire tunnel diodes. Crystal growth was carried out in two opposite directions: GaInP-Zn/InP-S and InP-Sn/GaInP-Zn, using Zn as the p-type dopant in the GaInP but with changes to the n-type dopant (S or Sn) in the InP. Secondary electron and electron beam-induced current images obtained using scanning electron microscopy indicated the presence of p-n junctions in both cases and current-voltage characteristics measured via lithographic contacts showed the negative differential resistance, characteristic of band-to-band tunneling, for both diodes.

GaAs Nanowire pn-Junctions Produced by Low-Cost and High-Throughput Aerotaxy.

Semiconductor nanowires could significantly boost the functionality and performance of future electronics, light-emitting diodes, and solar cells. However, realizing this potential requires growth methods that enable high-throughput and low-cost production of nanowires with controlled doping. Aerotaxy is an aerosol-based method with extremely high growth rate that does not require a growth substrate, allowing mass-production of high-quality nanowires at a low cost.

Time-resolved photoluminescence characterization of GaAs nanowire arrays on native substrate.

Time-resolved photoluminescence (TRPL) measurements of nanowires (NWs) are often carried out on broken-off NWs in order to avoid the ensemble effects as well as substrate contribution. However, the development of NW-array solar cells could benefit from non-destructive optical characterization to allow faster feedback and further device processing. With this work, we show that different NW array and substrate spectral behaviors with delay time and excitation power can be used to determine which part of the sample dominates the detected spectrum.

The effect of Sb-surfactant on GaInP CuPt type ordering: assessment through dark field TEM and aberration corrected HAADF imaging.

We report on the effect of Sb on the microstructure of GaInP layers grown by metal organic vapor phase epitaxy (MOVPE). These layers exhibit a CuPt single variant ordering due to the intentional misorientation of the substrate (Ge(001) substrates with 6° misorientation towards the nearest [111] axis). The use of Sb as a surfactant during the GaInP growth does not modify the type of ordering, but it is found that the order parameter (η) decreases with increasing Sb flux.