Superconductivity in AuNiGe Ohmic contacts to a GaAs-based high mobility two-dimensional electron gas
Superconductivity in AuNiGe Ohmic contacts to a GaAs-based high mobility two-dimensional electron gas
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DOI：
10.1063/5.0028217
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发表时间：
2020-10-19
影响因子：
4
通讯作者：
Ritchie, D. A.
中科院分区：
文献类型：
--
作者：
Beauchamp, C. B.;Dimitriadis, S.;Ritchie, D. A.
为了将GaAs-AlGaAs异质结中的高迁移率二维电子气（2DEG）冷却到毫开尔文温度，我们制作了基于Au、Ni和Ge合金的低电阻欧姆接触。欧姆接触在4.2K时的典型接触电阻RC约为0.8 Ω，低于0.9K时降至0.2 Ω。扫描电子显微镜图像确定，接触具有相同的不均匀的微观结构，已在以前的研究中观察到。接触电阻RC、沿单接触顶部沿着的四端电阻和垂直电阻R-V的测量都表明，欧姆接触中存在超导体，在0.15T的磁场下，它可以完全转变为正常。我们简要地讨论了这种超导性如何可能会影响电输运测量的2DEG，特别是它如何可能会阻碍冷却的电子在低于0.1K的2DEG。
To cool a high mobility two-dimensional electron gas (2DEG) at a GaAs-AlGaAs heterojunction to milliKelvin temperatures, we have fabricated low resistance Ohmic contacts based on alloys of Au, Ni, and Ge. The Ohmic contacts have a typical contact resistance ofR C approximate to 0.8Omega at 4.2K, which drops to0.2Omega below 0.9K. Scanning electron microscope images establish that the contacts have the same inhomogeneous microstructure that has been observed in previous studies. Measurements of the contact resistanceR C, the four-terminal resistance along the top of a single contact, and the vertical resistance R-V all show that there is a superconductor in the Ohmic contact, which can be turned completely normal with a magnetic field of 0.15T. We briefly discuss how this superconductivity may be affecting the electrical transport measurements of 2DEGs, especially how it may hinder the cooling of electrons in a 2DEG below 0.1K.