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An all-optical technique has been used to provide the first direct measurement of anisotropic minority-carrier diffusion in an ordered alloy of GaInP. Direct imaging of the minority-carrier diffusion distribution resulting from generation at a quasipoint source is obtained using an optical microscope coupled to a scanning electron microscope. Minority-carrier diffusion lengths ranging from 3 to 60 μm are measured by this technique in double heterostructures of GaInP, GaAs, and GaInAs, providing a key parameter of interest to the performance of state-of-the-art triple junction solar cells. Here we show a direct measurement of anisotropy in minority-carrier mobility in ordered GaInP, which is evident in the oval-shaped distribution of the recombination luminescence. A factor of 1.6 increase in minority electron mobility along the [110] major axis is reported. [ABSTRACT FROM AUTHOR]

[Display omitted] • Laser-powder bed fusion (L-PBF) fabrication of functionally graded nickel-titanium (NiTi)-AISI 316L material demonstrated. • Excellent bonding between NiTi and AISI 316L alloys controlled via complex bands of multi-material layers. • Phase and microstructural evolution controlled through the L-PBF settings. • Multi-material phase and microstructure formation/evolution mechanisms elucidated. This study evaluates the phase and microstructural evolution of additively manufactured (AM) Nickel Titanium (NiTi) alloy, across the interface with 316L stainless steel build plate, in order to understand the processing parameter (input power, layer thickness and scan speed), composition, and microstructure interrelationships necessary to achieve excellent multi-material bonding between NiTi and 316L. The effect of the process parameters utilised was characterised using the Scanning Electron Microscope (SEM), Electron Backscatter Diffraction (EBSD), X-ray diffraction (XRD), and Energy-dispersive X-ray spectroscopy (EDX). SEM/EBSD results demonstrated, for the first time, that the microstructure and phase close to the interface was complex and comprised martensite, austenite and Fe phases, sequentially arranged in a layered sandwich pattern across the build direction. This complexity was necessary for excellent bonding. The L-PBF process parameters influenced the diffusion behaviour and the concentration of elements found at the interface. The diffusion rate of Fe and Ti across the NiTi-316L interface was 3.05 × 10 - 6 m 2 / s and 3.27 × 10 - 8 m 2 / s , respectively, representing a 93.27-fold increase. The observed microstructural and phase evolution is related to the generated interface chemistry and the thermomechanical history related strain resulting from the L-PBF process. [ABSTRACT FROM AUTHOR]