Ge epitaxy at ultra-low growth temperatures enabled by a pristine growth environment

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Main Authors: Wilflingseder, Christoph, Aberl, Johannes, Navarette, Enrique Prado, Hesser, Günter, Groiss, Heiko, Liedke, Maciej O., Butterling, Maik, Wagner, Andreas, Hirschmann, Eric, Corley-Wiciak, Cedric, Zoellner, Marvin H., Capellini, Giovanni, Fromherz, Thomas, Brehm, Moritz
Format: Preprint
Published: 2024
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author Wilflingseder, Christoph
Aberl, Johannes
Navarette, Enrique Prado
Hesser, Günter
Groiss, Heiko
Liedke, Maciej O.
Butterling, Maik
Wagner, Andreas
Hirschmann, Eric
Corley-Wiciak, Cedric
Zoellner, Marvin H.
Capellini, Giovanni
Fromherz, Thomas
Brehm, Moritz
author_facet Wilflingseder, Christoph
Aberl, Johannes
Navarette, Enrique Prado
Hesser, Günter
Groiss, Heiko
Liedke, Maciej O.
Butterling, Maik
Wagner, Andreas
Hirschmann, Eric
Corley-Wiciak, Cedric
Zoellner, Marvin H.
Capellini, Giovanni
Fromherz, Thomas
Brehm, Moritz
contents Germanium (Ge), the next-in-line group-IV material, bears great potential to add functionality and performance to next-generation nanoelectronics and solid-state quantum transport based on silicon (Si) technology. Here, we investigate the direct epitaxial growth of two-dimensional high-quality crystalline Ge layers on Si deposited at ultra-low growth temperatures ($T_{Ge} = 100^{\circ}\mathrm{C}-350^{\circ}\mathrm{C}$) and pristine growth pressures ($\lesssim 10^{-10}\,\mathrm{mbar}$). First, we show that $T_{Ge}$ does not degrade the crystal quality of homoepitaxial Ge/Ge(001) by comparing the point defect density using positron annihilation lifetime spectroscopy. Subsequently, we present a systematic investigation of the Ge/Si(001) heteroepitaxy, varying the Ge coverage ($θ_{Ge}$, 1, 2, 4, 8, 12, and 16 nm) and $T_{Ge}$ ($100^{\circ}\mathrm{C}$ to $300^{\circ}\mathrm{C}$, in increments of $50^{\circ}\mathrm{C}$) to assess the influence of these parameters on the layer's structural quality. Atomic force microscopy revealed a rippled surface topography with superimposed grainy features and the absence of three-dimensional structures, such as quantum dots. Transmission electron microscopy unveiled pseudomorphic, grains of highly crystalline growth separated by defective domains. Thanks to nanobeam scanning x-ray diffraction measurements, we were able to evidence the lattice strain fluctuations due to the ripple-like structure of the layers. We conclude that the heteroepitaxial strain contributes to the formation of the ripples, which originate from the kinetic limitations of the ultra-low temperatures.
format Preprint
id arxiv_https___arxiv_org_abs_2410_03295
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Ge epitaxy at ultra-low growth temperatures enabled by a pristine growth environment
Wilflingseder, Christoph
Aberl, Johannes
Navarette, Enrique Prado
Hesser, Günter
Groiss, Heiko
Liedke, Maciej O.
Butterling, Maik
Wagner, Andreas
Hirschmann, Eric
Corley-Wiciak, Cedric
Zoellner, Marvin H.
Capellini, Giovanni
Fromherz, Thomas
Brehm, Moritz
Materials Science
Mesoscale and Nanoscale Physics
Germanium (Ge), the next-in-line group-IV material, bears great potential to add functionality and performance to next-generation nanoelectronics and solid-state quantum transport based on silicon (Si) technology. Here, we investigate the direct epitaxial growth of two-dimensional high-quality crystalline Ge layers on Si deposited at ultra-low growth temperatures ($T_{Ge} = 100^{\circ}\mathrm{C}-350^{\circ}\mathrm{C}$) and pristine growth pressures ($\lesssim 10^{-10}\,\mathrm{mbar}$). First, we show that $T_{Ge}$ does not degrade the crystal quality of homoepitaxial Ge/Ge(001) by comparing the point defect density using positron annihilation lifetime spectroscopy. Subsequently, we present a systematic investigation of the Ge/Si(001) heteroepitaxy, varying the Ge coverage ($θ_{Ge}$, 1, 2, 4, 8, 12, and 16 nm) and $T_{Ge}$ ($100^{\circ}\mathrm{C}$ to $300^{\circ}\mathrm{C}$, in increments of $50^{\circ}\mathrm{C}$) to assess the influence of these parameters on the layer's structural quality. Atomic force microscopy revealed a rippled surface topography with superimposed grainy features and the absence of three-dimensional structures, such as quantum dots. Transmission electron microscopy unveiled pseudomorphic, grains of highly crystalline growth separated by defective domains. Thanks to nanobeam scanning x-ray diffraction measurements, we were able to evidence the lattice strain fluctuations due to the ripple-like structure of the layers. We conclude that the heteroepitaxial strain contributes to the formation of the ripples, which originate from the kinetic limitations of the ultra-low temperatures.
title Ge epitaxy at ultra-low growth temperatures enabled by a pristine growth environment
topic Materials Science
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2410.03295