Flip-chip-based microwave spectroscopy of Andreev bound states in a planar Josephson junction

Hinderling, M.; D., Sabonis,; Paredes, S.; Z., Haxell, D.; Coraiola, M.; Kate, S. C. ten; Cheah, E.; F., Krizek,; Schott, R.; Wegscheider, W.; Nichele, F.

doi:10.48550/arxiv.2212.11164

Cited by 1 publication

(3 citation statements)

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“…The smoothness of the SE surface in the HAADF STEM image indicates that the presence of the boundary is not associated with neither a surface step nor a crystallographic defect in the semiconductor. These partially polycrystalline Al films performed consistently with previous reports in literature in our transport experiments which rely on the combined SE/SC system [30][31][32][33]. On the other hand, consistent results were achieved only when processing temperatures did not exceed 175 • C. This is due to degradation of both the Al film and the SE/Al interface, which was investigated by in-situ annealing of a lamella prepared from the standard material in a scanning transmission electron microscope.…”

Section: Al Thin Filmssupporting

confidence: 89%

“…Overall, we found that all three material designs exhibited a highly transparent interface, gap size comparable to the BCS theory and other reports in literature, signatures of coherent ballistic transport through a JJ and a good performance in our other experiments focused on InAs/Al hybrids [31][32][33]. In addition, studying differently designed material structures implemented into hybrid devices is important for further understanding of the influence of individual material parameters on transport properties.…”

Section: Effect Of Roughening On Transport Propertiessupporting

confidence: 85%

“…In our case, we grew a thicker bottom barrier, upper barrier and QW. Yet, the SE/SC coupling in such a structure remained on a scale relevant for our transport experiments [30][31][32][33]. We observed that the behaviour of our proximitized devices exceeds the theoretical limits given for specific barrier thicknesses in Ref.…”

Section: Growth Of the Semiconductormentioning

confidence: 82%

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Control over epitaxy and the role of the InAs/Al interface in hybrid two-dimensional electron gas systems

Cheah¹,

Haxell²,

Schott³

et al. 2023

Preprint

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In-situ synthesised semiconductor/superconductor hybrid structures became an important material platform in condensed matter physics. Their development enabled a plethora of novel quantum transport experiments with focus on Andreev and Majorana physics. The combination of InAs and Al has become the workhorse material and has been successfully implemented in the form of one-dimensional structures and two-dimensional electron gases. In contrast to the well-developed semiconductor parts of the hybrid materials, the direct effect of the crystal nanotexture of Al films on the electron transport still remains unclear. This is mainly due to the complex epitaxial relation between Al and the semiconductor. We present a study of Al films on shallow InAs two-dimensional electron gas systems grown by molecular beam epitaxy, with focus on control of the Al crystal structure. We identify the dominant grain types present in our Al films and show that the formation of grain boundaries can be significantly reduced by controlled roughening of the epitaxial interface. Finally, we demonstrate that the implemented roughening does not negatively impact either the electron mobility of the two-dimensional electron gas or the basic superconducting properties of the proximitized system.

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Section: Al Thin Filmssupporting

confidence: 89%

Section: Effect Of Roughening On Transport Propertiessupporting

confidence: 85%