Design Of Two-dimensional GaGeTe Film And Manipulation Of Quantum Property

Motivated by the sucessful synthesis of layered GaGeTe materials in experiments,we perform first-principles calculations to explore the geometric and electronic properties of GaGeTe few-layers,with a focus on the monolayer.The GaGeTe monolayer obtains favorable dynamic and thermal stability.With the reduce of thickness,a transition from semimetal to semiconductor occurs with a band gap increases to 0.74 eV.Moreover,the indirect band gap of the GaGeTe monolayer can be effectively tuned,which decreases with the increase of tensile mechanical strain applied,while increases and turns into a direct band gap under a compressive strain of 2.0%.Anisotropic carrier mobility can be observed along zigzag and armchair directions of the GaGeTe monolayer,and particularly for the former,it reaches a maximum of7.83×10⁴cm²v^-1s^-1.These findings provide great potential for applications of GaGeTe films in electrode materials and semiconductor devices,which also expands their potential applications in two-dimensional nanoelectronics.Considering that both GaGeTe and germanene have high carrier mobility,we investigate the physical property of Ge@GaGeTe heterostructure.Considering the relative position between GaGeTe and germanene,we construct three differnet Ge@GaGeTe configurations.By means of first-principles calculations,we find that the GaGeTe film is an ideal substrate for germanene deposition,and three herterostructures show semiconductor property.Ge@GaGeTe heterostructure possess a high carrier mobility(9.7×10³ cm²v^-1s^-1),and its band structures can be tuned by external electric field and strain engineering.Therefore,the predicted Ge@GaGeTe heterostructures are promise for designing FET data memory,which supplies new way for novel nano-electronic devices.On the other hand,based on tight-binding model and density functional theory,the geometric structure,electronic and topological properties of two-dimensional hexagonal m-Tl film are studied.We find that all Tl atoms locate in the same plane.Analysis of band dispersion reveals a Dirac nodal-ring near the Fermi level,which is attributed to p_x,y/p_z band crossing.When taking into account spin-orbit coupling effect,a band gap of 0.168eV can be observed.A transition from trivial to nontrivial state occurs when the tensile strain is applied to m-Tl film.Such topological nature is confirmed by berry curvature,edge states and Z₂invariant.Besides,we further reveal the origin of topological property of m-Tl film through tight-binding model.This study extends the scope of 2D elemental topological insulators and presents a platform to design new 2D topotronics materials.