Correlating <i>in situ</i> RHEED and XRD to study growth dynamics of polytypism in nanowires

Jakob, Julian; Schroth, Philipp; Feigl, Ludwig; Humaidi, Mahmoud Al; Hassan, Ali Al; Davtyan, Arman; Hauck, Daniel; Pietsch, U.; Baumbach, Tilo

doi:10.1039/d1nr02320a

Cited by 3 publications

(1 citation statement)

References 49 publications

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“…GaAs nanowires usually adapt the ZB crystal structure with the presence of short WZ segments at the nanowire bottom due to the small size of the droplet at the beginning of the growth, and at the nanowire top section due to As consumption which precedes radial shell growth [27,31]. However, the WZ Bragg reflection is not visible in later XRD reciprocal space maps, and therefore the nanowire crystal structure is considered to be pure ZB.…”

Section: Sample Preparation and Growthmentioning

confidence: 99%

Bending and reverse bending during the fabrication of novel GaAs/(In,Ga)As/GaAs core–shell nanowires monitored by in situ x-ray diffraction

Al Hassan,

AlHumaidi,

Kalt

et al. 2024

Nanotechnology

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We report on the fabrication of a novel design of GaAs/(In,Ga)As/GaAs radial nanowire heterostructures on a Si 111 substrate, where, for the first time, the growth of inhomogeneous shells on a lattice mismatched core results in straight nanowires instead of bent. Nanowire bending caused by axial tensile strain induced by the (In,Ga)As shell on the GaAs core is reversed by axial compressive strain caused by the GaAs outer shell on the (In,Ga)As shell. Progressive nanowire bending and reverse bending in addition to the axial strain evolution during the two processes are accessed by in situ by X-ray diffraction. The diameter of the core, thicknesses of the shells, as well as the indium concentration and distribution within the (In,Ga)As quantum well are revealed by 2D energy dispersive X-ray spectroscopy using a transmission electron microscope. Shell(s) growth on one side of the core without substrate rotation results in planar-like radial heterostructures in the form of free standing straight nanowires.

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Section: Sample Preparation and Growthmentioning

confidence: 99%

Bending and reverse bending during the fabrication of novel GaAs/(In,Ga)As/GaAs core–shell nanowires monitored by in situ x-ray diffraction

Al Hassan,

AlHumaidi,

Kalt

et al. 2024

Nanotechnology

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Electrically‐Driven Light Source Embedded in a GaP Nanowaveguide for Visible‐Range Photonics on Chip

Lebedev,

Solomonov,

Fedorov

et al. 2024

Advanced Optical Materials

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The key components of photonic integrated circuits are nanoscale optica emitters and nanowaveguides. III‐V semiconductor nanostructures are considered as the most promising material platform for these components due to highly efficient luminescence and high refractive index, but the problem of emission coupling with waveguide is to be solved. In this work, the use of GaP nanowires (NWs) with different types of doping (GaP:Si or GaP:Be) is proposed as optical waveguides with directly integrated electrically‐driven light sources, solving the problem of emission‐to‐waveguide coupling. Single NWs are integrated with electrodes and pump electroluminescence by a tunnel junction allowing to study emission properties with nanoscale spatial resolution. Basing on the experiments on scanning tunnelling microscopy (STM), electron microscopy, time‐resolved photoluminescence micro‐spectroscopy, X‐ray diffraction, and STM‐induced electroluminescence, it is proven that GaP NWs exhibit different integrated light‐source on doping type of NWs. GaP:Be NWs contain inclusion of the crystalline wurtzite phase with a direct bandgap, and, thus, these NW regions can be considered as electrically‐driven nanoscale sources of light monolithically integrated into GaP NW‐based waveguides. Meanwhile, GaP:Si NWs work as optical waveguides capable of efficient light generation over the entire length of NW. The developed designs are promising for construction of integrated photonic circuits.

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Development of in situ characterization techniques in molecular beam epitaxy

Shen,

Zhan,

et al. 2024

J. Semicond.

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Ex situ characterization techniques in molecular beam epitaxy (MBE) have inherent limitations, such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber. In recent years, the need for improved accuracy and reliability in measurement has driven the increasing adoption of in situ characterization techniques. These techniques, such as reflection high-energy electron diffraction, scanning tunneling microscopy, and X-ray photoelectron spectroscopy, allow direct observation of film growth processes in real time without exposing the sample to air, hence offering insights into the growth mechanisms of epitaxial films with controlled properties. By combining multiple in situ characterization techniques with MBE, researchers can better understand film growth processes, realizing novel materials with customized properties and extensive applications. This review aims to overview the benefits and achievements of in situ characterization techniques in MBE and their applications for material science research. In addition, through further analysis of these techniques regarding their challenges and potential solutions, particularly highlighting the assistance of machine learning to correlate in situ characterization with other material information, we hope to provide a guideline for future efforts in the development of novel monitoring and control schemes for MBE growth processes with improved material properties.

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Correlating in situ RHEED and XRD to study growth dynamics of polytypism in nanowires

Abstract: Design of novel nanowire (NW) based semiconductor devices requires deep understanding and technological control of NW growth. Therefore, quantitative feedback over the structure evolution of the NW ensemble during growth...

Cited by 3 publications

References 49 publications

Bending and reverse bending during the fabrication of novel GaAs/(In,Ga)As/GaAs core–shell nanowires monitored by in situ x-ray diffraction

Bending and reverse bending during the fabrication of novel GaAs/(In,Ga)As/GaAs core–shell nanowires monitored by in situ x-ray diffraction

Electrically‐Driven Light Source Embedded in a GaP Nanowaveguide for Visible‐Range Photonics on Chip

Development of in situ characterization techniques in molecular beam epitaxy

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