Impact Of The Stress On Bulk Silicon And Silicon Nanowire Based On First-Principle Calculation

For the strained silicon technology is widely used in integrated circuits, we studied thephysics and electrical properties of bulk silicon, as well as silicon nanowire under stress bythe first-principles calculation, which is based on the density functional theory (DFT).Firstly, we calculated the band structures, the energy splitting at bottom of conduction bandand the band-gaps of bulk silicon under hydrostatic, biaxial and uniaxial stress. Accordingto the calculated band structures, we obtained the effective mass of electrons and holes,and then derived the corresponding conductivity effective mass. As a result, we found thathydrostatic stress has the majority effect on electron conductivity effective mass, while theimpact on hole conductivity effective mass is limited.Secondly, from the changes of the band-gap and effective mass, we analyzed theeffects of different stress on band-to-band tunneling. Compared with the change of theeffective mass, band-to-band tunneling rate is more sensitive to band-gap changes.Moreover, the biaxial and uniaxial stress on band-to-band tunneling effect is greater thanthe hydrostatic stress.Finally, we calculated the device density of states, the transmissions and the I-Vcharacteristics of unidirectional strained silicon nanowire under multiple given voltages.And the results indicated that the strain effect on transmission coefficient was smaller thanthe applied bias voltage. In addition, when the applied voltage between two electrodes waslarge enough, compressive stress enlarged the current through the silicon thin-film, buttensile stress showed a decrease trend.