TY - JOUR
T1 - Highly Transparent Gatable Superconducting Shadow Junctions
AU - Khan, Sabbir A.
AU - Lampadaris, Charalampos
AU - Cui, Ajuan
AU - Stampfer, Lukas
AU - Liu, Yu
AU - Pauka, Sebastian J.
AU - Cachaza, Martin E.
AU - Fiordaliso, Elisabetta M.
AU - Kang, Jung-Hyun
AU - Korneychuk, Svetlana
AU - Mutas, Timo
AU - Sestoft, Joachim E.
AU - Krizek, Filip
AU - Tanta, Rawa
AU - Cassidy, Maja C.
AU - Jespersen, Thomas S.
AU - Krogstrup, Peter
PY - 2020/11/24
Y1 - 2020/11/24
N2 - Gate-tunable junctions are key elements in quantum devices based on hybrid semiconductor-superconductor materials. They serve multiple purposes ranging from tunnel spectroscopy probes to voltage-controlled qubit operations in gatemon and topological qubits. Common to all is that junction transparency plays a critical role. In this study, we grow single-crystalline InAs, InSb, and InAs1-xSbx semiconductor nanowires with epitaxial Al, Sn, and Pb superconductors and in situ shadowed junctions in a single-step molecular beam epitaxy process. We investigate correlations between fabrication parameters, junction morphologies, and electronic transport properties of the junctions and show that the examined in situ shadowed junctions are of significantly higher quality than the etched junctions. By varying the edge sharpness of the shadow junctions, we show that the sharpest edges yield the highest junction transparency for all three examined semiconductors. Further, critical supercurrent measurements reveal an extraordinarily high ICRN, close to the KO-2 limit. This study demonstrates a promising engineering path toward reliable gate-tunable superconducting qubits.
AB - Gate-tunable junctions are key elements in quantum devices based on hybrid semiconductor-superconductor materials. They serve multiple purposes ranging from tunnel spectroscopy probes to voltage-controlled qubit operations in gatemon and topological qubits. Common to all is that junction transparency plays a critical role. In this study, we grow single-crystalline InAs, InSb, and InAs1-xSbx semiconductor nanowires with epitaxial Al, Sn, and Pb superconductors and in situ shadowed junctions in a single-step molecular beam epitaxy process. We investigate correlations between fabrication parameters, junction morphologies, and electronic transport properties of the junctions and show that the examined in situ shadowed junctions are of significantly higher quality than the etched junctions. By varying the edge sharpness of the shadow junctions, we show that the sharpest edges yield the highest junction transparency for all three examined semiconductors. Further, critical supercurrent measurements reveal an extraordinarily high ICRN, close to the KO-2 limit. This study demonstrates a promising engineering path toward reliable gate-tunable superconducting qubits.
KW - semiconductor-superconductor nanowires
KW - shadow junctions
KW - ballistic transport
KW - quantum computing
KW - Majorana bound states
KW - topological materials
U2 - 10.1021/acsnano.0c02979
DO - 10.1021/acsnano.0c02979
M3 - Journal article
C2 - 32396328
VL - 14
SP - 14605
EP - 14615
JO - A C S Nano
JF - A C S Nano
SN - 1936-0851
IS - 11
ER -