InAs/GaSb heterostructure is one of the systems where quantum spin Hall effect is predicted to arise. However, as confirmed by recent experimental studies, the most significant highlight of the effect i.e., the conductance quantization due to non-trivial edge states is obscured by spurious conductivity arising from trivial edge states. In this work, we present experimental observation of strong localization of trivial edge modes in an InAs/GaSb heterostructure which was weakly disordered by silicon delta-like dopants within the InAs layer. The edge conduction which is characterized by a temperature-independent behavior at low temperatures and a power law at high temperatures is observed to be exponentially scaled with the length of the edge. Comprehensive analysis on measurements with a range of devices is in agreement with the localization theories in quasi one-dimensional electronic systems.Topological Insulator (TI) is a new phase of matter that has attracted a great interest not only for fundamental scientific research but also for its potential applications. Specifically, the quantum spin Hall (QSH) insulator is a two-dimensional topologically non-trivial insulator that is theoretically predicted to manifest an insulating bulk but accompanied by dissipationless helical states at the edges [1,2]. These new class of materials provide an ideal platform for novel spintronic applications, quantum information, and quantum engine [3][4][5]. The QSH effect was first predicted and soon observed in band inverted HgTe/(Hg,Cd)Te quantum wells (QWs) [2,6,7], where a transition from normal to topological phase can only be tuned by the thickness of the HgTe QW. Among the new proposals for a QSH system, the InAs/GaSb bilayer QW heterostructure is favored as it benefits from high mobility, easy fabrication, and most importantly the tunability of the band structure by an electric field [8][9][10][11][12][13][14][15][16][17][18]. Particularly, by application of dual gates on top and bottom of the heterostructure, the Fermi level and the alignment between InAs conduction and GaSb valence bands can be controlled independently in such a way that a continuous transition from trivial to brokengap nontrivial insulator is possible [8,15].In the early experiments on InAs/GaSb double QWs, the edge conduction was overshadowed by relatively large residual bulk conductance [9]. Subsequent efforts to suppress the bulk conductance via localization of bulk carriers incorporated the introduction of Si impurities at the interface between InAs and GaSb quantum wells [12][13][14], Be doping in the QW barrier [19,20], or using low purity Ga source material for the GaSb layer [21,22]. These studies confirmed robust edge conduction, however whether the conduction was due to helical or trivial edge states was not proven. On the other hand, more recent works demonstrated the presence of edge transport also in the trivial phase of these heterostructures [16,17,23]. The experiments with different sample geometries and edge lengths concluded that the ed...

We present magneto-transport study in an InAs/GaSb double quantum well structure in the weak localization regime. As the charge carriers are depleted using a top gate electrode, we observe a crossover from weak anti-localization (WAL) to weak localization (WL), when the inelastic phase breaking time decreases below spin-orbit characteristic time as a result of enhanced electron-electron interactions at lower carrier concentrations. The same crossover is observed with increasing temperature. The linear temperature behavior of inelastic scattering rate indicates that the dominant phase breaking mechanism in our 2D system is due to electron-electron interaction.

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We report on transport properties of the controllable large area MoSO/Reduced graphene oxide(RGO) heterostructures electrodeposited on FTO substrates and its comparision with theoretical calculations on MoSo/Gr. I-V characteristics of the heterostructure made by P or n-type MoSO, exhibit Schottkey behavior in the interface similar to the MoS2/Gr ones. Theoretical calculations show significant effects of lateral layer size as well as layer number in the electronic properties. In monolayer MoS2/Gr by increasing the lateral size the energy gap disappears and the Fermi level shifts towards valence band. In the case of bilayer MoS2 on bilayer Gr structure, the Fermi level shift is again towards valence band but, the gap is slightly higher than the monolayer structure. We found that the experimentally obtained results for n-type MoSO/RGO results are qualitatively in agreement with theoretical calculations of the MoS2/Gr heterostructure. These results are beneficial to understand and design the high quality and low cost MoSO/RGO based electronic, optoelectronic and energy storage devices or cocatalysts.