边修饰Net-Y纳米带的电子结构及机械开关特性的应变调控效应

利用密度泛函理论和非平衡态格林函数相结合的方法,系统地研究了边修饰Net-Y纳米带的电子结构和器件特性的应变调控效应..计算表明:本征纳米带为金属,但边缘的氢或氧原子端接能使其转变为半导体.应变能有效地调控纳米带带隙的大小,适当的应变使能带结构从间接带隙转变为较小的直接带隙,这有利于光的吸收.应变也能改变纳米带的功函数,压缩应变能明显减小功函数,这有利于纳米带实现场发射功能.特别是应变能有效地调控纳米带相关器件的I-V特性,能使其开关比(I_on/I_off)达到106,据此,可设计一个机械开关,通过拉伸及压缩纳米带使其可逆地工作在“开”和“关”态之间.这种高开关比器件也许对于制备柔性可穿戴电子设备具有重要意义.

Strain engineering of electronic structure and mechanical switch device for edge modified Net-Y nanoribbons

Net-Y is a new two-dimensional carbon structure,which has attracted research interest recently.Here,we study the relevant AB-type ribbons with edge modification,focusing on their strain controlling effects on their electronic structure and device characteristics.Intrinsic ribbons are metallic,but hydrogen or oxygen termination can transform them into semiconductors.Applying strain can effectively control the band gap size,resulting in a transition from an indirect band gap to a smaller direct band gap under appropriate strain,favorably to light absorbing.Strain can also change the work function of ribbons,especially for compressive strains,the work function is lowered significantly,which is beneficial to the improving of the field emission behaviors of ribbons.The analysis demonstrates that the change in band gap size is closely related to the variation of bonding and non-bonding composition between atoms with strain,while the change of work function is due to the variation of the attraction force and repulsion force between atoms upon strain.More interestingly,the strain can significantly regulates the I-V characteristic of device based on related ribbons.Therefore,a strain-gated mechanical switch with a very high current switching ratio I_on/I_off can be obtained by making it reversibly work between the“on”and“off”states with stretching and compressing ribbons,which is of great significance in developing the logic circuits for flexible wearable electronic devices.