Abstract
We show, using density functional theory (DFT) calculations, that the Schottky barrier height (SBH) at the PtSi/Si interface can be lowered by uniaxial strain applied not only on Si but also on PtSi. The strain was applied to the (001) direction of Si and PtSi, which is normal for the interface. The SBH of the hole is lowered by 0.08 eV under 2% of tensile strain on Si and by 0.09 eV under 4 % of compressive strain on PtSi. Because the SBH at PtSi/Si contact is approximately 0.2 eV, this amount of reduction can significantly lower the resistance of the PtSi/Si contact; thus applying uniaxial strain on both PtSi and Si possibly enhances the performance of Schottky barrier field effect transistors. Theoretical models of SB formation and conventional structure model are evaluated. It is found that Pt penetration into Si stabilizes the interface and lowers the SBH by approximately 0.1 eV from the bulk-terminated interface model, which implies that conventionally used bulk-terminated interface models have significant errors. Among the theoretical models of SB formation, the model of strong Fermi level pining adequately explains the electron transfer phenomena and SBH, but it has limited ability to explain SBH changes induced by changes of interface structure.
Highlights
Schottky barrier metal-oxide semiconductor field-effect transistors (SB-MOSFETs) are considered one of the important candidates for post-CMOS technology.[1]
We show, using density functional theory (DFT) calculations, that the Schottky barrier height (SBH) at the PtSi/Si interface can be lowered by uniaxial strain applied on Si and on PtSi
We suggest that SBH can be lowered by uniaxial strain applied at both the channel and the source/drain and that the strain engineering is applicable for higher-performing SB-MOSFETs
Summary
Schottky barrier metal-oxide semiconductor field-effect transistors (SB-MOSFETs) are considered one of the important candidates for post-CMOS technology.[1]. Extensive efforts have been made to lower the SBH so that the adverse effects of SB that appear as reduced on-state current, decreased sub-threshold swing and poorer switching performance can be avoided. By choosing appropriate metal-silicides, low SBH was achieved (e.g., platinum silicide[2] Φp = 0.15-0.27 eV for p-MOS and erbium silicide[3] Φn = 0.24-0.28 eV for n-MOS). In order to outperform (show comparable on-state current level with) the conventional MOSFETs, the SBH should be close to 0 eV or even negative
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