Effect of Buried-Interface Preparation for Nb Superconducting Resonators on InP

Abstract

Substrate surface preparation is a key step in the fabrication of electronic devices. In III--V semiconductor platforms, e.g. used in HEMTs and lasers, removal of the native substrate oxide is extremely important, where improper removal will negatively affect end-of-line device performance. However, the impact of substrate preparation in hybrid superconductor--semiconductor (S--Sm) systems relevant to quantum information applications remains poorly understood. This study compares three surface preparations for the deposition of sputtered Nb films on InP: (i) no intentional oxide removal (control), (ii) \textit{in-situ} Ar⁺ milling, and (iii) S-passivation. \textit{In-situ} Ar⁺ milling reduces the O concentration at the metal--substrate (MS) interface, but also roughens the InP surface, increasing the effective thickness of the Nb--InP interface and promoting O incorporation through extended defects in the Nb film. S-passivation suppresses interfacial O more effectively while preserving a sharper and smoother buried interface. It also yields Nb films with higher superconducting transition temperatures and less structural damage than the Ar⁺-milled samples. Despite these materials improvements, the microwave response is comparable across the three preparations. At single photon powers, the highest internal quality factors, Q_i, are approximately 1.30×10⁵ (130k) for the control resonators, 9.7×10⁴ (97k) for the S-passivated resonators, and 8.4×10⁴ (84k) for the Ar⁺-milled resonators. These results suggest that the present devices are not primarily limited by dielectric loss at the buried Nb--InP interface.

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BibTeX RIS

BibTeX

@misc{kusher2026effect,
  title = {{Effect of Buried-Interface Preparation for Nb Superconducting Resonators on InP}},
  author = {Logan S. Kusher and Ding Peng and Zihua Zhu and Arunav Bordoloi and Axel Leblanc and Lukas J. Baker and Nichae Adnan and Jacob Issokson and Alvin Wang and Frederik Knudsen and Krishna Dindial and Melissa Mikalsen and Taha Kaleem and Andrei Vrajitoarea and Yingge Du and Patrick J. Strohbeen and Javad Shabani},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.13673},
  eprint = {2609.13673},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.13673},
  note = {CC BY 4.0},
}

RIS

TY  - UNPB
TI  - Effect of Buried-Interface Preparation for Nb Superconducting Resonators on InP
AU  - Logan S. Kusher
AU  - Ding Peng
AU  - Zihua Zhu
AU  - Arunav Bordoloi
AU  - Axel Leblanc
AU  - Lukas J. Baker
AU  - Nichae Adnan
AU  - Jacob Issokson
AU  - Alvin Wang
AU  - Frederik Knudsen
AU  - Krishna Dindial
AU  - Melissa Mikalsen
AU  - Taha Kaleem
AU  - Andrei Vrajitoarea
AU  - Yingge Du
AU  - Patrick J. Strohbeen
AU  - Javad Shabani
PY  - 2026
DA  - 2026/09/12
PB  - arXiv
DO  - 10.48550/arxiv.2609.13673
UR  - https://arxiv.org/abs/2609.13673
AB  - Substrate surface preparation is a key step in the fabrication of electronic devices. In III--V semiconductor platforms, e.g. used in HEMTs and lasers, removal of the native substrate oxide is extremely important, where improper removal will negatively affect end-of-line device performance. However, the impact of substrate preparation in hybrid superconductor--semiconductor (S--Sm) systems relevant to quantum information applications remains poorly understood. This study compares three surface preparations for the deposition of sputtered Nb films on InP: (i) no intentional oxide removal (control), (ii) \textit{in-situ} Ar^+ milling, and (iii) S-passivation. \textit{In-situ} Ar^+ milling reduces the O concentration at the metal--substrate (MS) interface, but also roughens the InP surface, increasing the effective thickness of the Nb--InP interface and promoting O incorporation through extended defects in the Nb film. S-passivation suppresses interfacial O more effectively while preserving a sharper and smoother buried interface. It also yields Nb films with higher superconducting transition temperatures and less structural damage than the Ar^+-milled samples. Despite these materials improvements, the microwave response is comparable across the three preparations. At single photon powers, the highest internal quality factors, Q_i, are approximately 1.30×10^5 (130k) for the control resonators, 9.7×10^4 (97k) for the S-passivated resonators, and 8.4×10^4 (84k) for the Ar^+-milled resonators. These results suggest that the present devices are not primarily limited by dielectric loss at the buried Nb--InP interface.
ER  -

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