本征氧化层对Si纳米板弹性模量的影响

Effect of Native Oxide on Elasticity of a Silicon Nano-Plate

采用能量法计算了表面不带氧化层的Si纳米板和表面带不同厚度氧化层的Si纳米板的杨氏模量.结果表明,表面带氧化层的Si纳米板杨氏模量随着板厚度的减小而增加,不带氧化层的则随之降低,但当板厚度增加时,它们都趋于一个定值123GPa.板的杨氏模量随表面氧化层层数的增加而上升,随着板厚度的减小,氧化层的影响起到了决定性的作用.当表面带氧化层的纳米板厚度为50nm时,板的杨氏模量随着氧化层层数的增加从120GPa上升到近200GPa.计算结果解释了目前报道的Si纳米板杨氏模量尺度效应不一致的原因.

A three-dimensional model of a silicon nano-plate with native oxide is proposed. The energy approach is used to obtain the Young＇s moduli of the silicon nano-plate with and without the oxide layer. It is shown that the Young＇s modulus of the nano-plate with surface oxide increases with the decrease of the nano-plate thickness,while that without surface oxide exhibits the opposite behavior. The reason is that the native oxide layer dominates the plate as it scales down to several nanometers. As the plate increases to 300nm,the Young＇s moduli approach 123GPa. The Young＇s modulus increases as the oxide thickness increases. When the thickness is 50nm, the Young＇s moduli are in the range of 120 to 200GPa.