Si1x

Si1x is a notation occasionally encountered in silicon-related literature, but it is not a standard chemical formula. The conventional way to express nonstoichiometry in silicon-containing systems is Si1−x, where x is a fraction between 0 and 1 representing the amount of sites that are vacant or occupied by dopants or defects. When Si1x appears, its meaning is highly context-dependent and not universally defined.

In many cases Si1x is a typographical or transcription variant of Si1−x used in datasets, graphs, or computational inputs where x is a placeholder for a defect or dopant fraction. In other contexts, authors may use Si1x deliberately to denote a composition on the silicon sublattice where a portion x of sites are affected by impurities or a secondary phase, yielding a silicon-rich or mixed-occupancy system. Because the symbol is ambiguous unless defined, readers should consult the source material to determine the intended meaning.

The parameter x, when defined, typically lies between 0 and 1 and influences material properties such as defect density, electrical conductivity, carrier concentration, and mechanical behavior. Si1−x (or any defined Si1x notation) is often discussed in relation to nonstoichiometric silicon, defect chemistry, and dopant effects in semiconductor science. See also Si1−xGe x, silicon nonstoichiometry, and site occupancy concepts for related context.