The Electric Properties Of Two-dimensional Semiconductor Ge Se Under External Fields

Since graphene was separated from graphite,two-dimensional(2D)layered materials have attracted much attention However it is difficult to be used as semiconductor devices due to the zero bandgap property of grapheme.Many other 2D materials have been studied to compensate the disadvantage of zero bandgap,such as transition metal dichalcogenides(TMDs)Boron Nitride and Black Phosphorus(BP).These 2D layered materials have excellent physical optoelectronic perperties,such as high carrier mobility,flexible,completely transparent,remarkable field-effect properties,anisotropy.IV-VI semiconductors have the similar structure with BP.These materials should have unique physical properties and device applications as BP..The bandgaps are between 0.5 ev-1.5 e V,which are consistent with the spectrum of the solar spectrum.At the same time their electronic structure are very sensitive to external conditions.By first principle method we will study the electronic properties of 2D GeSe under external electric field and strain.These materials can be used in multi-wavelength photo detectors,multi-wavelength transparent glass,solar cells and nano optoelectronic devices.In addition,we have study the spin-spin interaction and p-d hybrid of Mn-doped ZnSe nanobelt by analyzing the electronic structures.The results are as following:1.The electronic properties of 2D GeSe1)The band gap of two dimensional GeSe under external electric field.Under the action of electric field,the band gap of two-dimensional GeSe will be changed linearly according to the intensity of electric field.The band gap will be closed finally,while the location of the CBM and VBM are not changed.2)The band gap of two dimensional GeSe under external strain.Applied strain is also a useful way to change the electronic properties of material.Under external strain 2D GeSe transfers from indirect band gap semiconductor to direct band gap semiconductor.3)The electric properties of 2D GeSe under electric field and external strain.By appling external strain the band gap of GeSe changes from indirect to direct.,Then we apply vertical electric field to the direct bandgap system,and tune the direct band gap in a larger range.2.The effect of spin-spin interaction and p-d hybrid in Mn-doped ZnSe nanobelts on photoluminescenceBased on first-principle method we find spin-spin interaction and p-d hybrid have an important effect on the transition of electrons,the color and the mechanism of photoluminescence.