摘要:
利用第一原理平面波赝势法,对（InAs）1/（GaSb）1超晶格原子链的原子结构、力学特性、电子能带结构、声子结构和光学特性进行研究,并结合密度泛函理论数值原子轨道赝势法和非平衡格林函数法计算量子输运特性.与二维层结构的（InAs）1/（GaSb）1超晶格相比,（InAs）1/（GaSb）1超晶格原子链的能带结构有明显不同,在某些情况下表现为金属能带特性.对理想条件下（InAs）1/（GaSb）1超晶格原子链的力学强度计算表明,该结构可承受的应变高达ε=0.19.通过对声子结构的完整布里渊区分析,研究了（InAs）1/（GaSb）1超晶格原子链的结构稳定性.对两端接触电极为Al纳米线的InAs/GaSb超晶格原子链的电子输运特性计算表明,电导随链长和应变的改变而发生非单调变化.光吸收谱的计算结果表现出在红外波段具有陡峭吸收边,截止波长随超晶格原子链的结构而变化.预计InAs/GaSb超晶格原子链可应用于红外光电子纳米器件,通过改变超晶格原子链的结构来调节光电响应波段.
Abstract:
The atomic structure,the mechanical properties,the electronic band structure,and the phonon structure of（InAs）1/（GaSb）1 superlattice atomic chain are investigated by first-principles pseudopotential plane wave method,and the quantum transport properties are also calculated by the density functional theory numerical atomic orbit pseudopotential method in combination with nonequilibrium Green’s function formalism.Compared with two-dimensional layer structural（InAs）1/（GaSb）1 superlattice,the（InAs）1/（GaSb）1 superlattice atomic chains have obviously different band structures,and represent metal energy band characteristics in certain conditions. The calculated mechanical strength of（InAs）1/（GaSb）1 superlattice atomic chains indicates that such structures can sustain the strain as high asε= 0.19.The structural stability of（InAs）1/（GaSb）1 superlattice atomic chains is investigated by full Brillouin zone analysis for phonon structure.The electron transport calculations for（InAs）1/（GaSb）1 superlattice atomic chain segments in between Al electrodes show that the conductance exhibits nontrivial features as the chain length or strain is varied.The calculated optical absorption spectra represent precipitous cutoff absorptions in infrared regime,and the cutoff wavelength varies with chain structure. InAs/GaSb superlattice atomic chains are predicted to be applied to infrared optoelectronic nanodevices,modifying optoelectronic response wavelength range by changing the structures of superlattice atomic chains.
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