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  • 1
    In: Journal of Applied Physics, AIP Publishing, Vol. 132, No. 8 ( 2022-08-28)
    Abstract: We study the critical thickness for the plastic relaxation of the Si quantum well layer embedded in a SiGe/Si/SiGe heterostructure for qubits by plan-view transmission electron microscopy and electron channeling contrast imaging. Misfit dislocation segments form due to the glide of pre-existing threading dislocations at the interface of the Si quantum well layer beyond a critical thickness given by the Matthews–Blakeslee criterion. Misfit dislocations are mostly 60° dislocations (b=a/2  & lt;110 & gt;) that are split into Shockely partials (b=a/6  & lt;112 & gt;) due to the tensile strain field of the Si quantum well layer. By reducing the quantum well thickness below critical thickness, misfit dislocations can be suppressed. A simple model is applied to simulate the misfit dislocation formation and the blocking process. We discuss consequences of our findings for the layer stack design of SiGe/Si/SiGe heterostructures for usage in quantum computing hardware.
    Type of Medium: Online Resource
    ISSN: 0021-8979 , 1089-7550
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2022
    detail.hit.zdb_id: 220641-9
    detail.hit.zdb_id: 3112-4
    detail.hit.zdb_id: 1476463-5
    Location Call Number Limitation Availability
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  • 2
    In: Journal of Applied Physics, AIP Publishing, Vol. 134, No. 3 ( 2023-07-21)
    Abstract: The misfit dislocation formation related to plastic strain relaxation in Si or Ge quantum well layers in SiGe heterostructures for spin qubits tends to negatively affect the qubit behaviors. Therefore, it is essential to understand and then suppress the misfit dislocation formation in the quantum well layers in order to achieve high-performance qubits. In this work, we studied the misfit dislocation propagation kinetics and interactions by annealing the strained Si or Ge layers grown by molecular beam epitaxy. The annealing temperatures are from 500 to 600 °C for Si layers and from 300 to 400 °C for Ge layers. The misfit dislocations were investigated by electron channeling contrast imaging. Our results show that the misfit dislocation propagation is a thermally activated process. Alongside, the blocking and unblocking interactions during misfit dislocations were also observed. The blocking interactions will reduce the strain relaxation according to theoretical calculation. These observations imply that it is possible to suppress the misfit dislocation formation kinetically by reducing the temperatures during the SiGe heterostructure epitaxy and post-epitaxy processes for developing well-functional SiGe-based spin qubits.
    Type of Medium: Online Resource
    ISSN: 0021-8979 , 1089-7550
    Language: English
    Publisher: AIP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 220641-9
    detail.hit.zdb_id: 3112-4
    detail.hit.zdb_id: 1476463-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
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