Surface Gate-Defined Quantum Dots in MoS2 with Bi Contacts

Transition-metal dichalcogenides (TMDCs) are promising materials for nano and quantum devices, with performance dependent on electrical contacts and gate electrodes at cryogenic temperatures. In this study, we utilized semimetal bismuth as the contact metal to fabricate two types of devices based on MoS2-Bi: field-effect transistors (FETs) and quantum dot devices. We observed linear current-voltage characteristics in the FET devices at temperatures of 4.2 and 0.4 K, within the range of -0.03 to 0.03 V, essential for quantum devices. For the MoS2 quantum dot device, we utilized intrinsic Schottky barriers between MoS2 and gold as gate electrodes to form and control the quantum dots. Coulomb diamonds were observed in the MoS2 devices at temperature of 0.4 K, with extracted parameters matching our device design. Our simplified fabrication process eliminates the need for additional fabricate gate insulators steps, enhancing design flexibility and fabrication possibilities for advanced quantum devices, including vertically integrated systems.