Ultrathin superconducting MgB2 films are desirable for device applications such as hot electron bolometers (HEBs) and superconducting nanowire single photon detectors (SNSPDs), and for exploration of new quantum phenomena in reduced dimensions. High-quality epitaxial MgB2 films have been grown successfully using Hybrid Physical-Chemical Vapor Deposition (HPCVD). Recently, we have found that the films grown with HPCVD on the C-terminated SiC substrate show smoother surface with better grain connectivity than on the Si-terminated surface of SiC. We have further discovered that a thin MgO layer formed at the interface of SiC and MgB2 is likely the reason for this difference. In this talk, I will present the results of a systematic study on ultrathin MgB2 films grown on C-terminated SiC substrates by HPCVD, with nominal thicknesses ranging from 2 nm to 10 nm. Superconducting properties with Tc0 = 27.2 K and Jc(3K, 0T) = 2 × 107 A/cm2 were obtained in the nominally 2 nm films while its root-mean-square (RMS) roughness was 0.62 nm. The results show that HPCVD-grown ultrathin MgB2 films on C-terminated SiC are promising for device applications requiring ultrathin film superconductivity.
Xiaoxing Xi is Laura H. Carnell Professor of Physics at Temple University. Prior to 2009, he was Professor of Physics and Materials Science and Engineering at The Pennsylvania State University. He received his PhD degree in physics from Peking University and Institute of Physics, Chinese Academy of Sciences, in 1987. After several years of research at Karlsruhe Nuclear Research Center, Germany, Bell Communication Research/Rutgers University, and University of Maryland, he joined the Physics faculty at Penn State in 1995. His research focuses on the materials physics of oxide and boride thin films. He is author of over 350 refereed journal articles and 3 U.S. patents. He is a Fellow of the American Association for the Advancement of Science and a Fellow of American Physical Society. He was a recipient of the American Physical Society 2020 Andrei Sakharov Prize.
These seminars are brought to you by Experimental Spintronics & Low-dimensional Materials and Physics Lab.