NaCl的层厚度对NaCl-Si(111)界面电子特性的影响

Effect of the Thickness of NaCl Film on the Electronic Properties of NaCl Si(111) Interface

根据Ｙａｎｉｖ的界面理论，利用紧束缚近似下的格林函数方法，研究了绝缘体ＮａＣｌ的层厚度对ＮａＣＬＳｉ（１１１）界面电子特性的影响．结果表明，（１）Ｓｉ上覆盖一层ＮａＣｌ时，导致局域在Ｓｉ一边的价带态密度显著降低和导带态密度显著升高，这可能是由于ＮａＣｌ的离子性将Ｓｉ的价带电子排斥到导带的缘故；（２）当ＮａＣｌ层厚增加时，局域在Ｓｉ一边的态密度几乎不受影响，这与ＮａＣＬＳｉ（１１１）界面热垒形成和费米能级钉扎有关．

In terms of Yaniv's interface theory,influences of the thickness of the insulator NaCl film on the electronic properties of NaCl Si(111) interface are investigated by using Greens function method within the framework of the tight binding approximation.The results show that(1) a layer of NaCl over Si(111) can cause the local valence and conduction band densities of states on Si side falling and rising considerably,respectively,which may be due to the fact that the ionicity of NaCl drives the electrons inside valence band of Si into the conduction band;and (2) the increase in the thickness of NaCl film has little effects on the local densities of states on Si side,which is connected with the formation of interface barrier and Fermi level pinning