Schottky diodes on Si/sub 1-x/Ge/sub x/, Si/sub 1-x-y/Ge/sub x/C/sub y/ and Si/sub 1-y/C/sub y/ alloys

Abstract

In previous studies, we have investigated the Schottky barrier height of tungsten (W) on p-type and n-type Si/sub 1-x/Ge/sub x//Si as a function of Ge-content (0/spl les/x/spl les/33%) and Si/sub 1-x/Ge/sub x/ thickness for a given composition. The barrier height to n-type does not vary significantly while that to p-type follows the same trends as the band-gap: it decreases with x and the strain. In this study, we have extended our measurements to the ternary alloy Si/sub 1-x-y/Ge/sub x/C/sub y/ and to the binary alloy Si/sub 1-y/C/sub y/. The behavior of the barrier height W/Si/sub 1-x-y/Ge/sub x/C/sub y/ is similar to that of W/Si/sub 1-x/Ge/sub x/: for p-type, it increases with the strain relaxation induced by the incorporation of C while it remains constant for n-type. On the other hand, results on W/Si/sub 1-y/C/sub y/ are quite different, suggesting a change in the Fermi level pinning position.