A double quantum dot defined by top gates in a single crystalline InSb nanosheet*

Abstract

We report on the transport study of a double quantum dot (DQD) device made from a freestanding, single crystalline InSb nanosheet. The freestanding nanosheet is grown by molecular beam epitaxy and the DQD is defined by the top gate technique. Through the transport measurements, we demonstrate how a single quantum dot (QD) and a DQD can be defined in an InSb nanosheet by tuning voltages applied to the top gates. We also measure the charge stability diagrams of the DQD and show that the charge states and the inter-dot coupling between the two individual QDs in the DQD can be efficiently regulated by the top gates. Numerical simulations for the potential profile and charge density distribution in the DQD have been performed and the results support the experimental findings and provide a better understanding of fabrication and transport characteristics of the DQD in the InSb nanosheet. The achieved DQD in the two-dimensional InSb nanosheet possesses pronounced benefits in lateral scaling and can thus serve as a new building block for the developments of quantum computation and quantum simulation technologies.

Understanding the Morphological Evolution of InSb Nanoflags Synthesized in Regular Arrays by Chemical Beam Epitaxy

“…Low-dimensional InSb nanostructures have sparked interest in the past few years due to their potential applications in high-speed and low-power electronics [ 1 , 2 ], infrared optoelectronics [ 3 ], spintronics [ 2 , 4 , 5 ], quantum electronics [ 6 , 7 ], and topological quantum computation [ 8 ]. These applications stem from the outstanding intrinsic properties of InSb such as a narrow band gap (≅0.23 eV) [ 4 , 9 , 10 ], high bulk electron mobility (7.7 × 10 4 cm 2 /(V s)) [ 1 , 11 ], small effective mass ( m ∗ = 0.018 m e ) [ 4 , 11 , 12 , 13 , 14 , 15 ], and a large Landé g-factor ( |g ∗ | ∼50, [ 11 , 15 ]). Among the most influential developments are the topological superconducting quantum devices based on InSb nanowires (NWs) [ 16 , 17 ].…”

Josephson Diode Effect in High Mobility InSb Nanoflags

“…In this context, Indium Antimonide (InSb) represents a valid platform. InSb has a narrow band gap (0.23 eV), 33,37,38 a small effective mass (m * = 0.018 m e ), 33,[39][40][41][42][43][44] and exhibits a strong SOC and a large Landé g-factor (|g * | ∼ 50). 45 In InSb 2D nanostructures, a similar value is measured in the out-of-plane direction, while the in-plane value g * ip is reduced by a factor 2, independently on the crystallographic direction (g * x ∼ g * y ∼ 25).…”

Gate-controlled Supercurrent in Ballistic InSb Nanoflag Josephson Junctions

“…InSb has a narrow band gap (∼ 0.23 eV). [6][7][8] It also has a very high bulk electron mobility (7.7 × 10 4 cm 2 /(Vs)) 9,10 and a small effective mass (m * = 0.018 m e ), 8,9,[11][12][13][14] which are both important requirements for high-speed and low-power electronic devices. 10,15 Finally, it also exhibits a strong spin-orbit interaction and a large Landé g-factor (|g * | ∼ 50, 9,14 ) and thus it is useful for spintronics applications 8,15 and for the creation of hybrid structures hosting topological states, like Majorana zero-modes.…”

“…However, until today only a few studies were reported on the growth and the electrical transport properties of such InSb nanoflags (NF). 7,9,13,19,[26][27][28][29][30] InSb NFs were first reported in 2016 by M. de la Mata et al 9 their growth being based on molecular beam epitaxy (MBE). There, the authors attributed the 2D geometry of the NFs to a single twinning event in the otherwise pure zinc blende structure of the InSb sam-ple, and four-terminal electrical measurements revealed an electron mobility greater than 12000 cm 2 /(Vs).…”

“…28 Quantum transport and quantum-dot geometries in such nanostructures were also demonstrated very recently. 7,[31][32][33] S. Gazibegovich et al combined selective-area growth with the vapour-liquid-solid mechanism in metal organic vapour phase epitaxy, leading to the formation of InSb NFs thanks to the development of a twin-plane boundary. 19,34 The same group reported evidence for crossed Andreev reflections in JJ made from such flakes.…”