Fabrication of Al/AlOx/Al junctions with high uniformity and stability on sapphire substrates

Fuente: arXiv
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Autori principali: Zheng, Yuzhen, Li, Shuming, Ding, Zengqian, Xiong, Kanglin, Feng, Jiagui, Yang, Hui
Natura: Preprint
Pubblicazione: 2023
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author Zheng, Yuzhen
Li, Shuming
Ding, Zengqian
Xiong, Kanglin
Feng, Jiagui
Yang, Hui
author_facet Zheng, Yuzhen
Li, Shuming
Ding, Zengqian
Xiong, Kanglin
Feng, Jiagui
Yang, Hui
contents Tantalum and aluminum on sapphire are widely used platforms for qubits of long coherent time. As quantum chips scale up, the number of Josephson junctions on Sapphire increases. Thus, both the uniformity and stability of the junctions are crucial to quantum devices, such as scalable superconducting quantum computer circuit, and quantum-limited amplifiers. By optimizing the fabrication process, especially, the conductive layer during the electron beam lithography process, Al/AlOx/Al junctions of sizes ranging from 0.0169 to 0.04 μm2 on sapphire substrates were prepared. The relative standard deviation of room temperature resistances (RN) of these junctions is better than 1.7% on 15 mmx15 mm chips, and better than 2.66% on 2 inch wafers, which is the highest uniformity on sapphire substrates has been reported. The junctions are robust and stable in resistances as temperature changes. The resistances increase by the ratio of 9.73% relative to RN as the temperature ramp down to 4K, and restore their initial values in the reverse process as the temperature ramps back to RT. After being stored in a nitrogen cabinet for 100 days, the resistance of the junctions changed by1.16% in average. The demonstration of uniform and stable Josephson junctions in large area paves the way for the fabrication of superconducting chip of hundreds of qubits on sapphire substrates.
format Preprint
id arxiv_https___arxiv_org_abs_2305_10956
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Fabrication of Al/AlOx/Al junctions with high uniformity and stability on sapphire substrates
Zheng, Yuzhen
Li, Shuming
Ding, Zengqian
Xiong, Kanglin
Feng, Jiagui
Yang, Hui
Superconductivity
Quantum Physics
Tantalum and aluminum on sapphire are widely used platforms for qubits of long coherent time. As quantum chips scale up, the number of Josephson junctions on Sapphire increases. Thus, both the uniformity and stability of the junctions are crucial to quantum devices, such as scalable superconducting quantum computer circuit, and quantum-limited amplifiers. By optimizing the fabrication process, especially, the conductive layer during the electron beam lithography process, Al/AlOx/Al junctions of sizes ranging from 0.0169 to 0.04 μm2 on sapphire substrates were prepared. The relative standard deviation of room temperature resistances (RN) of these junctions is better than 1.7% on 15 mmx15 mm chips, and better than 2.66% on 2 inch wafers, which is the highest uniformity on sapphire substrates has been reported. The junctions are robust and stable in resistances as temperature changes. The resistances increase by the ratio of 9.73% relative to RN as the temperature ramp down to 4K, and restore their initial values in the reverse process as the temperature ramps back to RT. After being stored in a nitrogen cabinet for 100 days, the resistance of the junctions changed by1.16% in average. The demonstration of uniform and stable Josephson junctions in large area paves the way for the fabrication of superconducting chip of hundreds of qubits on sapphire substrates.
title Fabrication of Al/AlOx/Al junctions with high uniformity and stability on sapphire substrates
topic Superconductivity
Quantum Physics
url https://arxiv.org/abs/2305.10956