硼氮原子取代掺杂对分子器件负微分电阻效应的影响

Effect of B and N doping on the negative differential resistance in molecular device

利用基于非平衡格林函数和密度泛函理论相结合的第一性原理计算方法,研究了硼氮原子取代掺杂对三并苯分子电子输运性质的影响.计算结果表明,三并苯分子器件的电流在特定偏压区间内随电压的增加而减小呈现出负微分电阻效应,电流的峰谷之比高达5.12.用硼原子或者氮原子取代分子的中心原子后,器件0.8 V以内的电流明显增加,但是负微分电阻效应减弱,相应的电流峰谷比分别降至3.83和3.61.分析认为,输运系数在特定偏压下的移动是器件负微分电阻效应的主要成因.核外电子数的差异导致硼氮原子掺杂取代可以使器件轨道及其透射峰分别向高能方向或者低能方向移动从而有效地调控了器件的低偏压下的电子传输能力和负微分电阻效应.

By using nonequilibrium Green＇s functions in combination with the density-functional theory,we investigate the effects of B and N doping on the transport properties in phenalenyl molecular device.The calculated results show that negative differential resistance behavior can be observed in phenalenyl molecular device where the device current can decrease with the base voltage increasing particularly in a bias voltage region,and the peak-to-valley current ratio reaches up to 5.12.The device current can be increased before 0.8 V when the molecular center atom is replaced by B or N atom.But,the negative differential resistance behavior can be weakened and the peak-to-valley current ratio can decrease to 3.83 and 3.61,respectively.The doping effects of B and N,which are induced by the difference in extranuclear electron number between them,can make the orbitals and corresponding transmission peaks move toward high or low energy to modulate the electronic transport ability and the negative differential resistance behavior of the device.